No consperacies, no ripp-offs, no cheating ...
Its a workflow model which is designed to be as productive as possibly can, within the least amount of time at reasonable cost. And that goes for the customer too.
Any other suggestion (fix this first, drop everything until ...,etc) is nowhere near as efficient and cost effective.
Yes, there are drawbacks and negative sides to it. But any other "system" would produce much more unconveniences.
And before someone says: "hire more people" ... that also comes with a price tag.
A price you are paying for ...