There's a trick that allows you to "build up" a large stock of raids. Each day you send all your raids at a sector 24 hours away, then right before they hit that sector teleports somewhere else or activates a protection item. The raids you sent are all returned to you, in addition to the 9 you regenerated while they were traveling. You can save up as many raids as you want this way, then use them all in one week.
There's a trick that allows you to "build up" a large stock of raids. Each day you send all your raids at a sector 24 hours away, then right before they hit that sector teleports somewhere else or activates a protection item. The raids you sent are all returned to you, in addition to the 9 you regenerated while they were traveling. You can save up as many raids as you want this way, then use them all in one week.