Well it generally seems to work out pretty well, and honestly 90% of the time I am talking about only searching 4-5 provinces, depending on if there are nearby waste or swamp.
Honestly, I've noticed that gem income is so sporadic, that it's essentially impossible to expect anything to occur reliably. So you look at what you want, and what you've got, and you meet somewhere in the middle - then hopefully it is enough to crush your opponents.
I also often do my Rainbows Dormant, as the extra 150 points allows a heap more paths/scales, and I just do the few manual searches when he gets out, and proceed from there. I think the situations are very rare, and very specific, where you can do more with 300-350RP, than you can with 150 design points. (EDIT - forgot there were 2 separate threads, though I stand by this next point
Though C'tis, with their ability to leverage skellie spam, is probably one of those where it's worthwhile to be Awake, and then research up to Ench3 fast, THEN do some manual searches.