Children are not the most efficient when it comes to spurting out lotion or soap out of a pump. They use their full force on the pump, which is why the lotion is splashed out and there is often too much for the kid to use. Then, they end up wasting the lotion and you are left ruing the wasted lotion due to your child's negligence.
The best way to go about here is to have a rubber band positioned just under the pump to stop your children from spurting out too much lotion. Not only would the lotion be saved this way, but you will also be safe from your children rubbing the excess lotion on any surface near the pump. So, be intelligent and have an eye on your children as they do these tasks.