Thanks! :)
The time between a tower spawn is randomly chosen between 0,1-5 seconds because when i was testing the "system" having a constant delay didn't eel good. There's also an RNG choosing if a tower should be placed or not, but since the time between each placement was eventually made to be random, I removed* the first RNG that determines if the tower should be placed.
*actually i just set the chance for tower to spawn to 100% because it was much easier and faster.
The 5 seconds interval between you recieve more coins was chosen because it felt te best when compared to 1-3 sec. intervals
The bad game speed/pacing is caused by lack of time to do proper testing.