Do You Have a Timer for Concentration?

Pomadoros are 90 minute blocks, while pommodoro is more like 25 five. The idea of a Pomadoro block can be different for each person depending on their skill set and how much sleep they got the night before. Stephen cutler talks all the time about pushing his flowblock to two or three hours. But what i caution people to away from is ah, this idea that i need to go hard for a really long time throughout the day to be productive.