Creating accountability is definitely a solid strategy, but I've got to point out that I absolutely procrastinate all of the things you mentioned in your first several paragraphs.
For ex: You need to spend 3 hours and write a 5 page report that is due on Monday at 9:00 AM.
You spend the whole week not working but feeling guilty about not making progress. Then suddenly in the last minute i.e a few hours before the deadline i.e around 5:00 AM to 8:00 AM you start panicking and make progress. You turn in less than stellar report.
With a contract based strategy you still procrastinate. But the end result is much better. i.e You need to finish 2 pages by the middle of the week or you pay $25 per missed page. Another 2 pages in the second half of the week. This way you still procrastinate and occasionally you pay the penalty but still you would be done with the essay/ report 2 days in advance rather than the last minute where the consequences are way higher in terms of getting a bad grade/losing scholarship/not graduating/ not getting into a better career etc.
That's the major problem with setting up timers or schedules or other obligation mechanisms yourself. If they're in your control, you're given as much freedom to remove them as you have to set them up in the first place.
If no amount of self-restraint or anti-postcrastination systems can get me to do something I tell myself I want to do, then maybe I either need to have someone force me to do it or realize that what I say I want in life is wrong. Maybe this is because I've been trained so that about the only thing left that's 100% effective for getting intrinsically boring work done is someone else forcing me to do something.
https://www.youtube.com/watch?v=2paoNvG5Nmo
In this guy's case he was able to run a successful startup and his brother was able to get into and graduate from Harvard despite being terrible procrastinators. (because of the strategy.) He was not using a monetary based strategy. Basically he placed a hit on himself via his brother and viceversa to become successful.
Another thing he did was to write a letter to his ex and told his brother to mail it if he did not finish a certain task.
Again.. these are terrible examples. I would not advocate violence or stunts like this. In my own case, I used money but for others it could be anything. Any consequence they would like to avoid.