@Alex ******
There is no leeway!
You are allowed to report afterwards for some days, but that does not mean you can stay over 90 days in a row without reporting.
Some immigration office might take time, some others it is within 5 minutes.
Preparation does not really take time, fill in an easy TM47 and make copies of TM30, passport and visa.
And you are right, only if you really want to travel you might travel outside every 90 days, but for preventing 90 days reporting that seems a bit overkill.
I would not plan my trips in such a way to prevent TM47 reports