That is a valid concern, yet also easily circumvented by doing checkrides in a rental, and doing most of one's hours in the experimental.

Ownership in general, in the walter-mitty state, usually involves something fast, aerobatic, turbine powered, with teleporters from orbit, a full galley and a gymnasium, and of course, supersonic flight. The reality is a single-seat or two-seat low-power recip airplane that doesn't break the bank (as much). Everyone wants the biggest, fasted retractable-gear, multi-engine firebreather...at first, then pares down to something realistic. The time-worn counsel is buy what you'll fly most that matches the majority of your missions. We want that family-hauler, but if we're only going to do that once in a blue moon, maybe rent for that one-off special occasion, and own something that matches what we'll be doing the rest of the year (like flying around the pattern, or landing in the back country, or low-orbit up-and-backs). Thus, get that small experimental and fly the wings to ragged shreds, and in the rare circumstance that something else is needed, rent it for the occasion.

That means, for those doing flight training, that one should train as one takes one's checkride...for that instrument rating, for example, do the training in the same panel-radio setup that you'll be using for the checkride, so it's familiar, one is proficient, and one stands the best opportunity for a successful ride. If one is "building hours" (I hate that term; build experience, not hours), go get that Corbin Baby Ace and fly it until your parker pen runs out of ink.