I think I sprayed too much primer for my first coat when painting my cabinets. What should I do next?
The smoother it is before each coat, the better the coat will look. I run my fingers over the surface while sanding to find and remove imperfections that aren’t visible.
If 120 grit is slow, go with 80 grit, then 120, then 240 and finish with 320 or even 400. For between coats you should only need a very light sand with 400.
(Instead of buying 400 grit, you can keep your used 320 grit since they get smoother before becoming useless).
Painting requires patience and practice. All paint behaves slightly different and the air temperature/humidity will also affect it.