Delivering projects / initiatives on time is a skill of knowing when to step on the brakes, slow down, and clean up things and make it production worthy.
If you are sprinting trying to get more feature squeezed in all the way until the finish line, then you don’t have time to slow down, polish up things and launch; oops, you just ran over the line.
Yes, if you slow down, you will deliver fewer features, but you WILL deliver a defined business value on time. What is an alternative?
My above statements obviously have different meanings within the waterfall vs. agile development methodologies, but the overall essence is the same.