That's actually pretty interesting to know, these 5 mins break every 30 mins.
To answer, no i tend to draw non stop for like 3 / 4 hours, and as i have deep anxiety disorders and a bit of nervous depression with it, drawing allways helped me relax and evade my own health problems and some of my life "problems" too.
As of now, talking about my schedule is... i have no schedule for now, because it's the winter and it became very... what's the word... wonky ? troubled ? Especially when winter depression is getting the best of me for now and with a lot of my health problems, i can only sleep in the day, working a lot at night, or when i wake up, so it's like, i draw for 3 / 4 hours, i take a break, i'm too exhausted to draw, my bed is near my computer so when i feel weak i just sleep, if i try to sleep at night it's too cold for me to breath (it's a social location house, meaning it's a dirt cheap house with a low bill but the isolation is pretty bad and there is a lot of humidity in the walls, also i am very allergic to dust and acarians and i have psoriasis from anxiety on my whole scalp, i try not to scratch anything it makes things worse xD ) and i get exhausted from "forcing" to breath so i kind of draw / live the night and sleep in the morning. (anyway i get dizzy and stunned with anxiety / anti depressive for a part of the day and my lines are... not as good as some other times )
But not to worry too much about that when spring comes most of these health problems kind of dissipate with the weather becoming better, i can go out more often and breathe normally, i get less stressed, it's really, really winter that is pretty bad for me.
I think i should use some alarm or something like this to force me taking breaks because being most of the time on my own, i can't keep track of the time i'm spending drawing just like you so, i need something as a reminder, i really need to get up more often and try to exercise to get more energy in my system, i take multivitamins in the winter, it helps trying to stay awake longer.
I would take walking breaks every 2 / 3 hours or so, but you suggest doing this more often than that, i'm writting everything down and try new routines based on other people experience with this.
Edit : Also it's pretty interesting to know that he has been doing this for 55 years, so it comes from a very long experience and might hold very serious roots on how to manage your health / time and actually allow the brain to step out of the work and step in with, maybe, a different perspective