I am also a long time Reaper user. I use FX sends for any process FX that needs to be in parallel or shared between multiple track groups. Classic examples are Parallel Compression for drums, unification reverbs. I will also use specific FX like EQ and compression on tracks alone but this doesn't stop me from also sending from these tacks as well or putting FX on a group buss. As most things need layers of processing and the processing layers are also intended to colour the sound. I do whatever combination acheives the results I am aiming for.
Best regards Mark