How do you intend to deal with spells that are not designed purely for in-encounter use? Examples could be Hallow, Alarm, Wall of Stone, Permanent Image, Discern Location, See Invisible, Teleport, Planar Binding/Ally, Forbiddance, Spider Climb, Fly, Sending, Charm Person, Suggestion, Major Creation, Remove Disease etc, etc, etc.
You'll need to put some sort of limitation on this sort of thing or else do some serious thinking what the implications of near-unlimited utility magic means in terms of your world setting. A world where any level 1 apprentice wizard living comfortably in the city can cast unlimited Charm Persons on passers-by, for instance, would be a rather scary place...