by gmg159
For me with Swarmlings late digging upgrade generally isn't just for VP, but if it was worth 0 VP I likely wouldn't do it.Often there are a few hexes needed late to finish off a town or two for swarmlings. If you need 3-4 digs to finish off towns 2 & 3 you can often get about the same result development-wise taking act6 and a hard 3 worker dig as you can by upgrading digging twice and using all 1 worker digs (and taking act3). The key to getting the same result is that you already have sufficient priests and coins, which for swarmlings is often the case. So development-wise you aren't really any worse off, and you are up 12 VP.
I personally like round 5 digging upgrades when possible (usually you need to spend priests by this point on something other than cults since you need to return those priests to your supply). Then you can usually count on the lightly contested act3 in both rounds 5 and 6 if you need it (you may not even need it both rounds with the worker influx from forming the towns).