with it doubling in size every 20 mins it doesn't take (potentially at least) long to cause a problem
It quite interesting working out how much 1 oz of slime would turn into in 24 hours if it doubles in mass every 20 mins :-)
In one hour you have 8 oz
In two hours 64 oz
in three hours 512 oz
etc
After 24 hours you have 2^72 oz
2^72 = 4,722,366,482,869,645,213,696 oz
Gee that really would be a problem