Exterior renovations are constraint problems. The roof you are keeping, the brick you cannot paint, the neighbourhood's general register — they rule out more options than taste does, and the render makes those constraints visible immediately. Siding changes, window trim, entrance upgrades and a fresh scheme are where exterior renovations earn their money, and all of them preview well from one good facade photo. For paint specifically, the AI House Painter runs colour schemes with more control than this page does.
Interior renovations are sequence problems. Surfaces, cabinetry, lighting and fixtures interact — new counters make old cabinet fronts look worse, better lighting exposes tired paint. Rendering the whole room renovated at once shows you the finished state the piecemeal upgrades are supposed to add up to, which is exactly the picture a room-by-room budget tends to lose.
The Fixer-Upper Rescue mode is for the hardest case: a property in genuinely poor condition — an inherited house, an auction listing, a neglected rental. It renovates from damage rather than from datedness, which is a different visual job, and it answers the question those properties always pose: is there a good house under there? Seeing the restored version of the actual building, not a comparable, is usually the moment that decision gets made.