It depends on the series for me. For the stuff I’m actively following I tend to let the single issues collect over time and then read a bunch at once. I’ve got a giant stack next to my bed right now that I still need to get through o__o
If it’s a series I’m only kinda in to I’ll let graphic novels build up and then read them all at once. One of the greatest disappointments is when graphic novels skip issues cause I’m completionist and I want everything together. Or when graphic novel collections get randomly cancelled.
If I’m only vaguely interested I’ll wait until a whole series is on sale at comixology and then read them digitally.