I am old school. I check on first startup for the day. Engine , diff ,and radiator fluid, I have had leaks in all three that needed watching. Power steering is once a month.
Also when getting on a strange vehicle, ESPECIALLY a hire machine. I have found low oil and saved myself a load of hassle.
About as often as I check the oil in my truck. Neither of them leak or burn oil, so almost never.
I check the bar oil in my chainsaw something like 8 times a day (when I'm using it.) I'm compulsive about it. I always want to run out of gas before bar oil.
Persistence in checking fluid levels and looking underneath for leaks can save you a huge repair bill down the road. All my tractors get a check of all fluid levels before I start them, no matter what and TIRE PRESSURE get's checked at least weekly, some thing that most owners never bother with but in my ag application tire pressure impacts ground compaction so I check it often.