In May this year we were down in WDW with our three kids and the in-laws ( total 7). Knowing the possibility of getting 'only' the full size, we reserved two cars (ended up with a blazer and Aurora, by the way). I checked both lotsat MCO, from lot to lot it was less than a ten minute walk by my six foot energetic standards. Both lots were offering the same mix of cars. Our strategy was my wife and family stayed in one lot while I walked to the other. We kept in contact via cell phone. We waisted about an hour with this process, but did finally end up with the blazer in the first lot!
It is worth checking, but no way would I carry luggage or drag my family across the airport to check. If I did happen to find the 'perfect' car in the other lot, i would have rented and drove out and around to the other side. We are leaving in just a few days and will check both sides if the first aisle is bare. But the hour invested last time was not worth it, I will not take an hour to do it this time. We will make our choice from both aisles and no waiting.