Well, a lot of groups won't let you fly solo unless you've either flown within the previous month or do a circuit with another person - who may be a group member and is not necessarily an instructor. There are lots of debates about the wisdom of this...
I used to hire a 152 from a man who was a microlight instructor but not a group A instructor. He did my check rides and if I didn't fly for a month or two he would do my check circuits too. This was relatively sensible, but used to send me scatty if I was on e.g. day 29 and had to wait half a day before flying a check circuit. It's a large reason why I've just bought myself a single-place LAA aircraft.