From the recent AAR of Bob Vogel's 2-day Pistol Class:
Good trigger control is developed and mastered through dry fire. It is important to maintain the same firm grip used in live fire during dry fire sessions; he feels most shooters are far too lax with their grip when dry firing. Bob reports dry firing 8-10 times for each of the 20,000 rounds of live fire practice he averages each year. He uses 1/3 scale targets when dry firing, but does NOT use a timer. (emphasis mine)
The first person who mentioned the whole idea of ditching a timer for dry fire was Julie Golob. I'd never really thought about it before and had spent plenty of time chasing record speeds in dry fire. As soon as she was done explaining why she approached it that way, it was like a giant lightbulb going off in my head.