Yes the randomly received seals are great bonus for those who don't always do seal farming activities. But you only get it once per vana day, approx 45 mnts or so, most will get 2-4 seals per full session of 2 hours aby party. Most are so random that you may throw 75%-85% of them unless you are new to the game. Technically you only need to go back to the dominion ops officer to get the seals, if you get it right away, you don't need to go back again, so this can be a 10-40 mnts in between, longer if you get it immediately on the new day, shorter if you get it later on the day.