Three Laws of Ultrarunning?

After a super-busy stretch at work, I'm just now getting caught up on my blog reading. I came across an interesting comment on Anton Krupicka's excellent blog (see reader comments via this link). Anton has been battling injury and this particular reader cited the following training rules/laws he lives by as an ultrarunner:

1. It's better to be 20% undertrained than 1% overtrained
2. When in doubt, leave it out
3. When you are feeling like Superman, it's time to back off the training and take a rest week

Allow me to offer some observations on these rules. But first I'd like to say I see a lot of merit in these rules.

It's better to be 20% undertrained than 1% overtrained.
I'm going to have to disagree with this rule on the following premise: You don't want to be 20% undertrained or 1% overtrained; you want to be peaking come race time and this comes through strategic build-up, the right level of intensity at various stages in your training, and proper rest, recovery and diet. In other words, keep the needle just below the red! I guess what the reader is saying is that being tired from too much training is going to affect you more in a race than falling about 20% short of optimal fitness. I've never felt 20% undertrained, but I have felt 1% overtrained and I still managed a strong finish. My guess is that I'd prefer the latter. Besides, if you taper right, you can recover a ton over a period of 2-3 weeks before the event and go in fresh and strong. Just make sure your endocrine system isn't stressed--the signs include poor sleep, irritability, diminished sex drive, apathy, depression, etc. It can take several weeks or a few months for the endocrine system to come back.

When in doubt, leave it out.
I agree here. If you wake up in the morning and have an interval session at the track on your schedule but your legs feel like jelly, it's better to skip that workout and maybe go for an easy-pace run or cross-train (note that I didn't say take the day off, but that's an option, too). The track workout can wait until tomorrow. As Ryan Hall has said, let the training come to you--meaning don't force specific mileage or time goals on yourself if you're not feeling it that day. Do what you can. If your legs are toast and you hammer it at the track (been there, done that), you run the risk of injury. Listen to your body and its signals; if your legs are trashed, your body is telling you something. This is a training rule I've only recently fully embraced.

When you are feeling like Superman, it's time to back off the training and take a rest week.
I agree and disagree here. If I'm feeling like Superman, a big part of me will want to play this string out and see where it goes, so long as I--again--keep the needle just below the red. On the other hand, if you're feeling like Superman and push the envelope by running a few extra 1600s or going beyond the 10% rule, thereby going into the red, your risk of injury goes up. It's better, I think, to maintain self-control and know how to handle the good and bad days. But I can't agree that if you feel like Superman you should take a rest week. Great accomplishments almost never come from playing it safe.

Do you have any rules of running? If so, please share!