About how many times do you have to pump to empty contents?

For my use of it so far, I pumped it up to the stated thirty pumps at the beginning and only had to pump again after it was three quarters empty. Then I gave it roughly ten pumps, there was pressure remaining when it was empty.

Multiple times as it empties. When it is full about 5 pumps gets you started. You will need to apply additional pumps as the material you are spraying is used up. Air is required to fill the displaced fluid to maintain pressure.

Did not count the pumps but it was very easy to prime and continue spraying until the container was emptied.