First, I'm going to ask that these not be implemented until 6.1. While I would like to see them, I also don't want to wait another 4 months for 6.0.
These are mostly cleaned up and worked-out versions of things I posted back in the spring. I tried to flesh them out some to make them easier to implement.
1. Officer auto assignment.
Would it be possible to get the auto-assign to assign officers that don't have crew training ratings or the relevant abilities, after all the officers with relevant abilities are assigned? I tend to try to fill those slots, but in a large games, it's sort of a chore.
2. Crew rotation and pool tracking.
I find the current system to be incredibly simplistic. You have two levels, conscript and pool. Nothing else, and unless I'm mistaken, the the crew in the pool persists forever. Also, the crew will stay with a ship forever, and then magic people appear on scrapping. The entire system only makes sense if the crew are actually robots.
Here's my suggestion. First, the crew pool tracks people and points separately. The academy has a level that it pumps people in at. For example, it may add 100 people and 20000 points in a given week. These are added to the pool values. When a ship is commissioned, it takes the correct number of people and points, based on the pool averages. Adjusting the academy training level only affects the inflow, not what's already in the pool. Also, people should leave the pool. Maybe 5% a year, of average points. In wartime, you can check a box which temporarily slows the loss rate, but eventually (5 to 10 years later) it comes back to normal, or even goes higher. After you uncheck it, the war timer counts backwards until it reaches 0, so people don't just toggle it on and off when they get to the point of diminishing returns.
Second, rotate people on ships. To make it easy, whenever a ship gets shore leave, a certain number of people rotate back into the pool, based on how long it's been out. Maybe 10% per year. They're replaced with normal people from the pool. This is to avoid the "ICBM station with an enormous crew rating" problem.
Third, allow picked crews, and unpicked crews. These have maybe 150% and 50% of normal points, respectively, taking the appropriate number of people and points from the pool, and getting those values when the crew rotates. This is to allow you to have a good crew on your fancy new battleship, and give your second-line PDCs the dregs.
3. Automation of ships.
Automation has several effects. First, no crew required (obviously). Second, no onboard repair. Thirdly, no captain, and the crew grade is fixed, and set by the level of automation system you use. Fourth, there is a fixed "fleet training rating" that can't be altered, and is also set by the automation system. Fifth, docking with a crewed ship should be able to repair the vessel, and maybe reduce the maintainence clock some. Something like the shore leave system, where you have "time since last tune-up" and "time since last overhaul".
4. Task Force Training.
Have TF training drain off. It's entirely possible to train a ship up all the way, park it in orbit, and leave it there for a decade or two. I'd suggest having ships work up faster than they do today (maybe a year at training 100). The points persist as long as the crew is away from shore, but when they get to shore, the points start to drain off. After the shore leave timer is exhausted, the points drain at maybe 2% a month. This way, ships have to keep training occasionally. After a refit, for example, a ship would have to work up again to get back to full efficiency. The drain is slow enough that a ship would only have to go to sea about one month out of four.