The issue comes when the landlord (or agent) realises this. As a reward for your hard work they will expect more rent.
Absolutely! However I find myself with a good landlord who wants his ground farmed and kept tidy and is genuinely interested in helping me.
Pay £60 acre, and live on farm in caravan. I do remind him occasionally that the shed I put up and the roadway I put in and all the fence and grass improvements will be there when I leave (in a box) and he's happy with that....after all I am increasing the value of this tenancy for his family long term.
Couldn't rent a small flat/bedsit for twice the rent I pay here just to put everything in my perspective.