By scheduling the task:
1) It will happen in the background = more responsive backend
2) I will feel more comfortable that the migration will not be triggered several times (in case of heavy visited site)
I will just use it for the latest migration, as it is long time since last migration and only 15% of installations are old enough to gain on this improvement
By scheduling the task: 1) It will happen in the background = more responsive backend 2) I will feel more comfortable that the migration will not be triggered several times (in case of heavy visited site)