This post does not need to be long. If I can make a spaghetti carbonara in half an hour, it would be a mistake to think that I could make another and another and another each in half an hour one after the other. Once I have made my spaghetti carbonara, I need to wash up otherwise my sink will fill up and I will run out of cooking utensils. I need to clean the worktop surfaces otherwise I will run out of worktop space. If I neglect the clean-up part of the job I will very soon be hindered in the speed with which I can make another meal, the washing will build up and I will need to stop and attend to a mountain of cleaning.
Software and tech debt work in the same way.