Just wanted to ask about some guidelines on betting several sizings with different parts of your range. I'm guessing there definitely are obvious situations when it's really bad and situations where it poses obvious benefit.

I'm not talking about exploitative plays where we bet a little less with bluffs and a little more with value against clueless fish. Assume we have a capable villain who plays a large sample against us and is willing to adjust.

Could you share your knowledge on this topic?

I think that the wider the ranges involved are, the more betsizes one should utilize. So when ranges get very narrow, the bettor should have the nuts in range as well as potential bluffs, all of which should use the same betsize.

There's probably a correlation between number of combos in your range and the number of viable bet-sizes, so if you're in a spot where you have very few combos (e.g. on the river in a 4-bet pot), there's probably not much scope for "range-splitting".
If you give a solver a wide variety of bet-size options for a particular spot, I think it will often use most, if not all of them, at some frequency, and it would be quite rare to only use one for the entire strategy, or to discount some sizes entirely. That said, you'll rarely be missing out on massive amounts of EV if you just choose one size for your range and balance correctly. In most spots, using multiple sizes is only going to marginally improve the EV of the overall strategy, and it's incredibly difficult on a human level to visualize multiple parts of your range and play them all perfectly.
I haven't done much solver work, though, so someone with more experience might have found some spots where splitting (or avoiding splitting) is quite important.