I leave at least 30 min gaps between clients, have a coffee, shower, tidy room and answer texts.
I like working as in one after another with the 30 min gaps.
I find when you go quiet for hours , i then struggle to get into the motion again. For example say start at 10am, do A client at 10am (1 hr) client B at 1130am (30 mins), ClientC at 12:30 (1 hr). Then nothing until 6pm (I often work til 10pm / 11pm). That's That's 4 and half hr gap. Those gaps kill me. I get lazy and can't be arsed.