This year in Colorado so far hiking trails and camp sites have been way less utilized especially not on the popular weekends. The last 2 years it was as you described booking months in advance but so far this year you can nab a same day spot at most parks during the week and there is much more overall availability. Hiking trails and parks I've done are probably 30-40% as busy as they were this time last year. It definitely is starting to feel like people are moving on and doing other things this year.