Should You Add Jeju to a 7-Day Korea Trip?
Jeju can add a completely different side of Korea, but a seven-day trip is where the trade-off becomes real. Another flight, another airport transfer and weather flexibility all consume time that could stay with Seoul or a mainland second city.
Add Jeju when the island itself is a priority. Skip it when you are adding it only because it feels obligatory. On a short first trip, Seoul plus one mainland route can often feel less rushed.
What Jeju adds
Jeju offers a different landscape and travel rhythm from Seoul, Busan and Gyeongju. If nature, island scenery and a slower segment are central to the trip, it can be worth restructuring the itinerary around it.
What Jeju costs
The flight itself is only part of the cost. You also add airport access on both sides, check-in time, another hotel transition and a need for more schedule flexibility.
If removing Jeju makes the mainland trip noticeably better, Jeju probably belongs in a future trip. If removing Jeju removes the part you are most excited about, build the itinerary around the island.