Is it even possible for bookings to be full when it’s summer?

I went to consultations for revision eye surgery at ㅇㅇㅋ, ㅎㅂㄴ, ㄴㅅㅎ, ㅇㅁㄹ, and ㄸㅋ lol Among these, I liked ㅇㅇㅋ and ㄴㅅㅎ the most, so I asked both places about surgery dates. ㄴㅅㅎ said they can do it on a weekday next week, but ㅇㅇㅋ says they’re fully booked this month, haaaa Honestly, I like ㅇㅇㅋ a bit more, so I want to do it there, but is summer peak season or whatㅠ;;