Please don't do this. I see people doing it, even going so far as to leave flagging tape on obvious, maintained trails so they don't "lose their way". And usually people don't remove it after. It makes an area trashy, especially when done unnecessarily—and saying you should do it whenever you go off-trail is very unnecessary.
If your navigational skills are poor enough that you can't trust yourself to walk off-trail without getting lost, use a passive system like running a GPS receiver during your hike so you can backtrack along its track until you find your trail.
If your navigational skills are poor enough that you can't trust yourself to walk off-trail without getting lost, use a passive system like running a GPS receiver during your hike so you can backtrack along its track until you find your trail.