By saving something for the last moment, I increase my efficiency at that task through increased motivation. Let's say, for example, I have 6 hours and a 3 page paper to write. If I start that paper at the beginning and work constantly with no distractions, I'll probably finish in 2 hours, leaving 4 hours of extra time. This is because in my head, I know that I have plenty of time, so I will naturally overthink everything. I might spend 5 whole minutes trying to rephrase an awkward sentence because I can. I won't be very focused because I know I don't have to be: I have 6 whole hours!
So now let's switch sides and say I spent 5 hours not working, leaving only an hour to write it. In my brain, I would divide it up: 5 paragraphs, with 3 body paragraphs, an introduction, and a conclusion, meaning I can spend 10 minutes on the introduction, 15 on each body, and 5 minutes on my conclusion. This will be running through my brain as I type up the paper, so I will pace myself accordingly. My motivation will be to get it in on time and to get a good grade. Instead of typing the aforementioned awkward sentence, I will type it correctly the first time because my whole thought process will be going towards typing the paper well the first and only time, instead of thinking that I can always go over it later so it doesn't have to be perfect. Through this process, I will type nearly the exact same paper, but in only half the time, so in the long run I had a better overall experience in those 6 hours.
Then there's always the "But you'll do better if you leave yourself time!" But how much better? If I save myself time, I'm just writing pretty much the same thing at a slower pace. Of course there will be minuscule differences, but how much are they actually worth? Is it worth putting in an extra hour to raise a 94% to a 95%? For me, the answer is no. I would much rather have an extra hour and get a very slight grade drop than use that hour to get a 95. And then there's, of course, dealing with that one friend who's salty that he spent more time on something but didn't get a higher grade and that it's not fair, but what can I say? This is just the way that I work, and it is a system that works for me, so others should not mind how I do my work, as long as I eventually get it done and do well.
So anyway, that's my view on procrastination. Hope you learned a lil bit.