True. Unless you are using one of the bottles with an air release valve like the lost vape ones, refilling through the 510 takes a while.
Every time you squeeze liquid in through the 510, you have to wait for the trapped air in the squonk bottle to make its way back up into the refill bottle or break the seal, which can be messy.
But that's why you line up the little marks on the bottle to assist with the air influx

