In a previous thread, I finally learned that razor bumps can be brought about by either razor irritation or ingrown hairs. I was under the impression that they were mutually exclusive.
Well, to test the assertion I decided not to shave for a few days. My Sunday shave immediately gave me nominal razor bumps. They weren't catastrophic but obviously, I wasn't pleased. On Monday, most of the bumps had vanished except for a few habitual offenders on a specific section of my neck. By Tuesday, I had even fewer bumps. On Wednesday, I had more bumps again. They were very sensitive to the touch and felt swollen. Finally, today, the bumps are still there but not as sensitive or swollen.
From my experience, even though you can't get razor bumps from post-razor irritation and ingrown hairs concurrently, you can certainly get them in succession. For some with sensitive skin and very wiry, curly hair, it's quite the vicious cycle..