Slalom skis usually end up torsionally weaker and not holding an edge as well. Most consider this worser. If you’re not racing it, you really don’t know the extent until replaced.
Yeah, this^^^^^^. I notice some skis "seasoning," some of them more noticeably, some not, some for the better, some for need of base flattening, or edge adjustment, mostly. And they seem, to me, to get softer flexing lengthwise also, often.
With FIS SL skis especially: I get my race skis second hand, often "better than new," and one can often tell if a slalom ski was a practice ski (lots of use) or a race course ski (just used for the few actual runs on the courses), by both appearance and how soft it flexes, seems like. These SL skis break down much faster, apparently, being flexed so powerfully through so many turns, BOTH torsionally and lengthwise, I believe, and while they probably do break down more noticeably torsionally (for the worse), this can be compensated for to some extent more easily, IF the ski is just being used recreationally, by keeping the edge sharp and more immediate (through judicious use of base flattening and shallower/more progressive base beveling, to fit the ski now, based on one's own skier feedback: if it feels less edge-engaged in a certain way, one can partially correct for that, in the right areas, almost automatically, with practice, between ski days, on the tune bench.
With repeat tuning to fit ski performance, skis often can get more dialed in with time, in addition to faster with repeat waxing.