Planning a holiday in Korea and Japan next year. I as looking at flights from Japan to Seoul for July 2023, but it seems like the low cost Korean airlines all stop selling tickets in late March. Except for Korean Air and Asiana, which have their schedule for 300+ day. The rest all stop a little over 3 months from today. Is this common practice for Korean airlines?

Korea Air and Asiana are charging double what Jeju Air, Air Busan, T'Way, Jin Air and Air Seoul charge for the same flights. Should I wait until the July 2023 flights are released or the prices will stay around the same as Korea Air and Asiana for the summer months?