For me, it depends on my level of interest in the subject. If it's a passing interest, I'll do an OOB. If it's something that I've always been interested in, I'll go all out with resin, PE and scratchbuild.
Right now, I'm working on a 1/32 hellcat. I've spent more on resin and PE upgrades as well as styrene sheet/rod than I did on the kit itself.
I hate to do a breakdown like this because it forces me to see how much I've spent:
1/32 Hasegawa Hellcat - $38
miscellaneous styrene sheet and rod $35
hypodermic tube for gun barrels - $15
rectangular tube for ammo chutes - $11
Verlinden resin cockpit - $20
Eduard PE set (interior/wheel well) - $15
Eduard Mask - $4
and then throw in books and specialty color paints and tools and you can see how expensive hyper-detailing can get.
-Fred