As a very general rule o’ thumb…
I give my beginning clients the target of 5 hours of accumulated “intentional exercise” per week (as opposed to ‘incidental activity’.)
If they do more, the intensity usually goes down (depends on personal goals, obviously.)
If they can’t make it to 5, the intensity typically goes up.
Whether they “serve time” an hour or two at a pop or break it into several ‘doses’ of 10 minutes here, 15 minutes there usually doesn’t matter.