With the addition of new troops and spells, there are now 21 different troops/spells to upgrade. That's 108 total upgrades if you were to max all troops and spells. Most of these upgrades take 10+ days to finish. There should be at least one more slot or additional Laboratory to make this more reasonable with the additions of new troops and new levels in the past few years.
That's the progression of the game though. If you had more than one spot, it would make the game go too fast, and your run out of elixer upgrades faster.
