I agree Pace, it's all a load of pish.
From personal experience, I'd say fly the clubs 152's 172's and PA28's
during ppl. If a particular a/c goes u/s it leaves a plan B open.
Any competent 152 driver should be able to fly a 172 without little or no instruction. I know because I did, back in the days when you didn't need a check-out every time the bog roll in the toilet was changed.
The jump [if you can call it that] into a PA28 is just familiarisation with the panel and the manual flap lever. Other than numbers, that's it!