The lake I fish here in Ohio was a big crappie making machine from 2000 when I first starting fishing it regularly till about 2010. In August 2009 the state put 9" min length and 30 crappie a day limits on most Ohio lakes.
State proposing a size and bag limit on crappie
By 2011 the crappie started to be stunted in many of those reservoirs where the new restrictions were put into force. It was painfully obvious by 2015 that the regulations were stunting the crappie populations.
It took till the fall of 2018 to make changes to rescind those crappie length and bag limits on many of those lakes including the one I fish weekly from ice-out till ice up(March-Nov/Dec).
Ohio Wildlife Council makes changes to fishing size limits, seasons
I have noticed that in 2020 and especially last year the size on the crappie have grown larger and we are now catching the 12-13"ers with occasionally 15 or a 16"er with a mix of the smaller ones (these are slabs for Ohio).
Just keep in mind that length and bag limits don't work everywhere and even on close by bodies of water will have different results to limits. Especially if they are a high producing species like crappie. A local city reservoir where NO fishing is allowed that I used to occasionally commando fish is full of nothing but stunted populations of all species. Limits are not always the answer.
I commend the ODNR for recognizing their mistake and rescinding the crappie bag and size limits on many of the reservoirs.