Not all colony cost 2 worlds require equal amounts of work to make habitable. I found one that needed only a few percentage of ATM of additional oxygen to make it fully habitable. Other worlds have CC 2 from dangerous gases, CC 2 unbreathable and CC 2 from temperature - but it's still only CC 2, and requires a great deal more work to make habitable.
Also world size makes a big difference in level of effort to terraform. I have one world that recently became habitable, but the terraform ratio vs Earth was .85, and I had 2-3 dozen terraforming stations in orbit, each with 5 terraforming modules, for decades (I just kept building them).
Also consider that if for some reason you've decided that you want to inhabit a planet with small maximum population cap it might actually be more time efficient to simply churn out infrastructure that can house the entire planetary population and not bother with terraforming at all.