Needed, that's the wrong word. The bigger the better, it's a compomise about what you can comfortably do.
I just put fences at strategic points, so my 2 pairs of does, alternating, have the whole backyard, about 200m²,. They do a lot of digging though, but that doesn't matter to me.
My two house bunnies are free roam, in house and front yard, only restriction is that they have to be in the house at night.
I’ve got the same problem, I live in an old house with nooks everywhere so limited free roam and I’m thinking of maybe setting up my back veranda as a run. I put the litter tray near where he roams and usually goes to that.