Many of us will look at the ep price chart to get an idea of predicted crowd levels.
And when you see high prices for the onsite hotels, that also is an indicator.
those of us that have gone at different times of the year are aware of what to expect crowd wise.
reading about school holidays or breaks, also lets us know when more families will be in parks.
those little things add up and will help us suggest when we feel crowds will be there.