A litter box will need to be cleaned two-three times a week AT LEAST. Even then, it might start to smell every few days. Depending on what type of litter you use, and how thick it is on the litter box/pan, it'll be best for eliminating odor to clean the soiled part each day. It doesn't take a long time and your rabbit will thank you!
With outside bunnies who have bottom trays, the fresh air keeps the ammonia smell down better then the air in the house or in a barn/shed. That's why rabbits are always healthier outside. Bottom pans may only need to be cleaned once a week where the smell is concerned, but dumping the tray everyday will keep it from becoming a huge chore. It only takes a couple minutes per tray when it's done often enough.
Rabbits also poop A LOT! If your rabbit only poops in one corner of the cage, by the end of the week the poop will be piled high and start to come into the cage. By the beginning of next week, cleaning day, the rabbit may be stepping and sitting in its poop and urine, staining its paws and fur. It's filthy and unsanitary. The bottom trays should be dumped at least two times a week, for the bunny's sake.
I'm guilty myself of putting the cleaning off to the last minute. Rabbit urine and poop isn't the best part of raising rabbits, to say the least. Luckily, I'm reminded to clean before things get too bad, but I could still do it more often.
As to water bottles, food dishes and hay racks, they can be cleaned every week or two or as often as needed. I clean my water bottles each time I refill them (with a water bottle brush and hot water). My crockery bowls/hay racks I clean less often, every couple weeks or if poop gets stuck on the bottom or into the dish.
If there is any fleece in the cage (they usually don't chew it, unless they're too bored or if a tag is visible), it'll need to be shaken out and washed every couple of weeks as well. Fur and hay accumulate on fleece very quickly. I have two fleece baby blankets that I switch out; while one is being washed, the other is with my house bunny.
Once everything is clean, you can just sit back, relax, and enjoy your rabbit (until you need to clean everything again!). Isn't that what owning a rabbit is all about??