IMO the scientist's skill should still play a role for the time needed to complete a project other than simply needing less labs. A brilliant researcher working at the project's lab cap (e.g. 20 labs in his case) should still be faster than his mediocre collegue at his lab cap (e.g. 30 in his case).

And there should be a point as well where adding another lab does nothing for a project.

Maybe standard/minimum time based on research tier might do the trick, with racial techs being a percentage of those values and the researcher's skill being able to lower those times a bit. E.g. tier 5 research needs 5 years to complete at full efficiency (standard) and a minimum of 2 years, but a 60% researcher can bring those times down by an additional 12%.

How about using a time target for each project at base research speed to determine the optimal number  of labs. E.g. a project would take 20 years wih 1 lab at 100rp each year with perfect lab utilisation = 2000rp. So a 8k project could use 4 labs at 100% with the 8th lab at 50%, the 12th at 25% and the 16th providing no additional benefit. Higher research techs and research boni would still provide additional research and each research tech level would provide the opportunity to set up a special research project with can use twice the number of labs.

Using time as the baseline for diminishing returns is actually really smart. Because it scales automatically with higher cost techs requiring more labs.

For example you could use 5-6 years as "No penalty" research cutoff and gradually introduce diminishing returns the more below this you want to reduce research time. Down to 2-3 years there would not be a big penalty, but it would grow quickly if you try to reduce research time down to a matter of months.

For racial techs there could be half time = 3 years for "no penalty" ( since they are less complex then base research normally ).

Ok then It makes sense, but that is very similar as adding diminishing returns I guess. Lab number 20 would not be effective until after 1200 days = over 3 years. Overall now that I think more about it I think just diminishing returns would be more simple to display.

You can change the time to get things up and running faster. If you assume most players will want a research project done within, say, 5-10 years, 30 days per lab wouldn't be bad at all for 20-30 labs for early to moderate tech. You could also add technologies to decrease that time or link it to the RP generation tech or even scientist skill.

The code complexity comes when players start trying to find loopholes, for example start a new project with 1 lab, wait 60 days, then assign the remaining 19 labs...

You would of course need to account for any strange and odd behaviours.

In this instance I'm not so sure what you mean, when you add those 19 labs each lab will take 60 days to activate and only ONE will activate on the same project each 60 days. That is the whole purpose I suppose.

What you could do is...

Project X had 10 labs and is now finished.

You now assign 1 lab to project Y and 1 lab to nine other projects. After 60 days you remove one lab from one project and add it to project Y, you repeat this after 60 days until project Y have all ten labs.

You could do this to gain a small benefit while the labs are gearing up to that project you really like.

It is not perfect, but it will be very tedious to min/max the system at least so most will not do it and I think it would be against the spirit of the system as well.

There probably is a better way to handle it, more like how naval yards is used where you build more permanent lab complexes devoted to a specific field. You can change field but it will be very expensive and time consuming if the complex is large. Smaller complexes is faster to change and can be used for smaller research project such as components. There can also be a small gearing cost between project change but much smaller than changing the complex from one field to another.

You could now also lower the bonuses from the team and let each complex add some smaller bonus the longer it remain in the same field... or some such. The administration level of a research team could also have an impact on how efficient they can use different sizes of complexes. A team with a low administration level will get a negative bonus from using a larger complex.

I liked your idea of having the labs take some time to start working. This would waste some resources if you add many labs to one project at any one time instead of moving them more often but in smaller quantities.

Although waiting for getting the labs back on each 5 day cycle is perhaps not practical but waiting for them to start working you will not have to do anything.

Lets say you have to wait 30 days for each lab to become available if it is applied within the same field and 60 days if applied to a different field. This should not be a major code change I believe but it would significantly alter the way you view technology progression overall. Then remove 5 days for each administration level of the scientist leading the project.

you could use the scientist's political reliability bonus to give a positive bonus(to represent them successfully lobbing for more funds/other positive reasons) or negatively (bureaucratic infighting ect) when the project starts to make the research non liner and give a risk / reward to spice things up.

Perhaps the critical mass should be 1lab per 1000 RP needed for the research?

I did say that my example was a little silly...

But I think that we did reach a consensus regarding critical mass and anything you add after that will decline in efficiency, perhaps even rapidly in some cases. Critical mass is the resources you need to get the most bang for your buck sort to speak.

In my view one lab should be considered the critical mass, unless there were a specified critical mass needed that perhaps differ from project to project, but that I think is overly complicated and unnecessary.

Lab spool-up/spool-down time. A project could start get 1 lab a month working and, after the project is done, free up 1 lab a week (or whatever). If a project can only get so many labs "in-action" in a certain amount of time it discourages throwing large numbers of labs at a small project as many will not end up working. The spool-down time ensures that your labs are committed to the project. This still strongly encourages large numbers of labs for big projects as they will have time to spool up and operate at maximum efficiency.

Treat labs more like shipyards. There can be a cost associated with moving labs around or changing projects that encourages an appropriate number of labs scaled to the size of the project. Throwing large numbers of labs at small projects becomes cost-prohibitive.

Scale lab costs with the number of labs on a project. While they may not have reduced efficiency it may cost more to integrate and keep labs working together. This encourages smaller groups of labs, but utilizes wealth (which is very liquid) rather than research output (which is very difficult to modify quickly).

Reduce the number of labs available to researchers. As the first option listed, it would create a cap for the number of labs per project. Alternatively, make it a soft cap where more labs reduces efficiency if you go over the cap.

Those are some quick ideas. How do you feel about those? I think most will more strongly encourage scaling lab allocation to project size.

I like all of these suggestions, if not even better than what I said in my original proposal.