Where I come from, when you pay for services in full before the service being rendered is fully completed or even commenced, there’s the risk of not getting your job done in the end. Sometimes, you almost have to resort to tongue lashing the fellow(s) you’ve paid to do the job(s).
This thought extends to us as persons; we mostly get our best work done when there’s something to look forward to as reward for our undertakings.
Well, the bottom line is that there’s a very good reason gratification is delayed for endeavors we indulge in. If we had all the incentives in full even before we start any task, the drive to keep going might be lost.
Every step of the way, every activity of the day, one needs to have something ahead one’s working for, some prize to keep the motivating juices flowing.