Thanks for sharing!
Yeah, I think it’s definitely the case that you get better results if you set the goal such that earning safety days is tough but doable. I have my flossing goal set to 6 per week and I tend to average 6.5 per week. If it were set to 7 I would just derail all the time and probably average something like 2 per week.
Yeah I’ve mostly given up on Take a Break. I have switched to using the Beelint thing I hacked up. I can just mark my Google Calendar with a vacation block and it will complain at me if any of my goals have an eep! day that lands during the vacation. So then I know to work harder and build up a safety buffer or (less frequently) schedule a Take a Break.
The Take a Break default value for Do Less goals is double the regular slope. But when you enter a break you can type any number you want. So if you had replaced the 6 with a 0 you would have gotten a flat section.
Well…sort of… there’s still this rat’s nest of the road width changing when your slope changes. It’s very difficult to enforce a particular Do Less limit on any particular day, but things will usually roughly work out.
Well, the nice part of Take a Break is that your “progress” isn’t messed up in the sense that your cumulative total accomplished is still accurate. You have these safety days you didn’t earn, but your total stuff done isn’t inflated. I know you know this but I think it’s a nice thing!
I burned myself out on Beeminder in 2014 because I got so eager to Beemind everything I could possibly think of. Even just reading your notes about Anki makes me want to go download it and Beemind something with it. It requires some restraint to just leave it be. 
Damn, so I've gotten to the bottom of your double post and I realize that everything I've commented on is the same old meta how-to/troubleshooting stuff you were saying you think we already have too much of.
I am glad that you have turned your health situation around! I do wonder about consistency vs being realistic when it comes to friends in town or trips. I get into this mentality of "I want my typical week to look like X" where X is being healthy and working out, etc. But the list of exceptional circumstances is so long that I probably only have 10 typical weeks per year. So what does typical even mean then? And if I just Take a Break everything away, I never actually have to do my goals.