There's no magic number for needing a toad, though rather obviously the larger the motorhome the greater the inconvenience in using it for general transportation.
I don't use a toad with my 32' motorhome. For suburban or rural areas, it's not too inconvenient; I can park easily in any two front-to-back parking spaces in a parking lot. (A 29' would also need two parking spaces, I think, in most cases.) I would not want it in a large city, but then again I don't think I'd want any motorhome bigger than a class B in a large city.
I think it depends as much on how you approach camping and setting up camp. If your setup consists of pulling in and getting level and plugging in the electric, then disembarking for a trip is pretty quick. If, on the other hand, you hook up electricity and water and sewer and cable and deploy the awning and unroll an outside mat and hook the grill up to the RV tank and spread pink flamingos around and so on and so forth, it will naturally take rather longer to head out for the day. Likewise, if you don't tend to spend many days at one campsite, it's easier to run errands when you're on the road anyway than if you spend a couple weeks at each stop.
