This question was just asked on another forum. I will say it again. It TOTALLY depends on the lake. If it is shallow for a long way out, you will find most the stuff shallow. If there is a drop-off, you will find more stuff on the drop-off than you know what to do with, ESPECIALLY if the drop-off is a short distance from the swimming area. My best days have been on drop-offs where I have been the only one detecting.
If you find older pictures where there was swim platforms out in the water for kids to dive off (liability issue now) your going to have a blast at the bottom where it was anchored. If you are going to lakes that are hit hard by others, NO MATTER where it was lost you have to be one of the first to find it.
If you are an avid water hunter, don't just go to public swim areas. Find sandbars on the lakes, old unused swim areas and areas behind houses you can LEGALLY detect. You might not find much BUT you also might find an old swimming hole that nobody has detected. I pulled up over 20 gold rings and countless religious medals and silver coins behind a non discript home. It had to be a church camp at one time.
If you follow everyone else, be prepared to find what everyone else finds. New drops, new coins, and new trash. If you venture out on your own the possibilities are endless.
How many here have a Lewis Machine gun magazine, WW1 practice bombs, and numerous old lead toys and cars in their collections? How many can come back after a hunt with over 40 pieces of silver and 6 gold rings. Maybe NOW people don't venture past 4' BUT that was not the case in the 1900's - the 1960's. No air conditioning and NO TV, people actually got out and played more. Especially in the water on hot summer days.