I generally like to use the start of a project to see what’s new out there and research and test as much techniques as possible. Right now in Unreal the newest fad is Niagara, so that will be a completely new thing and it will take months until a proper set-up is done, so I probably won’t use it much.
But in terms of RnD, I personally look at other people’s work, also other mediums as well and try to see if I can recreate it somehow, tweak shaders, look at new functions, etc. To be fair a lot of those things drop at some point, because they just don’t seem to fit with some of the other things and I don’t really have something “groundbreaking” or “new” - just iterations of various things. This actually relates to my question I posted on your VFX course, about techniques and approaches - that always seems to be the case. Unlike 2D where you just draw (not saying it’s easy, but it’s obviously just drawn), here it’s like “Oh, this is awesome…how is it done???”
But it really depends how heavy the game is on VFX. I think that one of the heaviest VFX depended games was Infamous Second Son - if you look at the amount of work of technical tools they made, it’s really crazy.