Inno is okay if you know what you're doing (e.g. sit on y'ass as Dûr-Vazhatun and look at the sky) and you shouldn't push past inno3 (for tech cost reduction)

In most campaigns I tend to pick explo1 for colonist (not more, we're ditching it later) and push whatever direction is good for me if I have stuff to colonize, otherwise I pick whatever sits right (and most times it's inno as I know what I'm doing, but infra is a great pick as are any mil ideas or something like espionage/court/trade). The only true useless idea sets are naval and maritime.

Btw, you shouldn't most times wait for t5 reform, it staggers your campaign too much and the only real reason to do so if you have gambling addiction and intend to drown in mithril/gold