I think there are as many answers to the glue/no glue debate as there are 3D printer enthusiasts!
I’ve printed PLA Silk dual color on textured PEI before without glue, and it didn’t fuse. The only difference this time was that I skipped washing the plate; instead, I just wiped it with IPA and reapplied glue.
It’s always interesting to hear how others approach this, as it can help optimize our own printing methods.