I do it on purpose now, but I used to do this by accident of out of necessity all the time. Heat treating has changed things a lot as far as what I do and how I do it, along with the principle of never pulling a bow during tiller to more than its intended draw weight. BUT....
Most of my early selfbow efforts took more set than I wanted, but long before Marc wrote about it in TBB, guys were talking about heat treating, so I started doing it. I would start a bow, get it almost tillered, and see it start taking set, maybe 1-1/2 to 2". Then I would routinely either flip 6-8" of the tips forward 2" or so on a shorter to medium length bow (nothing like a real recurve, no string touching at brace) OR cook reflex into the first 2-3" off the handle , or into the handle, so the whole thing was reflexed. In either case I would then toast the whole limb straighter.
Heat treating reflex back into a badly set bow doesn't seem to restore it to me, and Marc says it doesn't, but it seems to at least freeze it in it's tracks. The first third of a limb or so often gets overworked, but that area right next to the handle up into the fades doesn't seem to, and can be set forward with heat. A little of that goes a long way, then I set the longer bows limbs straight on a board and the limb itself would take less set or stop settling at the least.
On the flipped tips, almost no bow design I was making bends much at all in those last few inches, so flipping 6" foreward didn't cause more set, didn't cost me stability , or require much tip weight. No downside except the risk of screwing it up, or maybe making the tip lean to one side if the cross section wasn't nicely symmetrical laterally. You gain string tension at brace and improve the F/D curve.
I still do this, but now I plan it rather than react to problems as I saw them.
