Bluegills on the beds?

Over the years, on Lake Monona, it's been easy in late May/early June to see the "bluegills on the beds". In the shallow flats like Turville Bay, where the bottom seems to be a bit sandy and a bit gravel-strewn you could easily see the round "beds" that the bluegills made. My question is about Lake Mendota. I have rarely seen such "beds". I do not fish Mendota as frequently but wondered what readers could tell me about this. Also, given that Mendota is bigger and slower to warm up, would bluegill spawning usually be a week or two later on Mendota than on Monona? Thanks for anything you could share.