No spells should be per encounter abilities. In the current implementation, it cripples the strategic level of the game. Upon reaching level nine, I am free to use some combination of level one spells in every encounter. This means I no longer have to worry about managing my level one spell resources, effectively eliminating a strategic layer from the game. More damaging, however, is the fact that per encounter spells allows one to save their higher level spells until they're really needed. At lower levels, there's a risk-reward mechanic in that the player has the option of using higher level spells in easier encounters to limit the health loss sustained by the frontline. In turn, this allows the party to push further without using resting resources, but at the expense of spell availability. The relevance of this mechanic diminishes post level nine because, from level nine onwards, the obvious strategy is to use some combination of level one spells in every encounter. Level one spells are potent enough that the player can rely on them to defeat easier encounters before significant health damage is sustained (let's not forget that all the other members of your party grow in strength as they level up too.) Selecting some limited number of spells to be per encounter abilities could work, but it strikes me as an inelegant approach with problems of its own. For one, it risks limiting the greatest strength of the wizard: their versatility. Forcing a wizard to pick per encounter spells forces the wizard to keep that spell in their grimoire permanently. I suppose this problem could be subverted by having per encounter slots in the grimoire (i.e. whichever spell the player fills that slot with becomes a per encounter ability). However, the main issue is that limiting the number of per encounter spells still has the negative consequence of making it a no-brainer strategy to spam those per encounter spells in every encounter. This seems worse than making all x level spells per encounter, because it inherits all the problems of that system but has the further consequence of limiting the player's spell choices.
