I do the best I can to print full frame.
I've marked a few standard heights on my enlarger. I enlarge 35mm, including rebates, to about a quarter inch from the 14 inch side of 11x14 paper. I just want to make the best possible image and I feel 35mm at 11x14 is getting near the limits of what the medium can handle. Before spawning another debate, let me qualify by saying that last summer I took a series on Panatomic-X 35mm which compares favorably to 4x5 - but everything has to be "right" for the 35mm to compare with the quality that 4x5 delivers easily.
I print 4x5 with an unfiled negative carrier to about a half-inch all around, with my paper easel out of the way so the negative carrier does the masking. I get a kind of border that looks like rebate, where the carrier edge reflects light off the neg. If I had a filed-out 4x5 carrier I would use it.
I don't envision leaving the rebate on display. Ultimately I want the mat to mask about 1/16 to 1/8 of the live image when framing. I want to have some tolerance for drift over time.
I try to have some bleed all around whith no significant image information risked in the last quarter inch. Beyond that little tolerance, I do like to put elements close to the edge. And I do like to use the native aspect ratio of the format.
I'm not dogmatic about it though, I shot some snapshots of a friend's wedding where I couldn't get into the right places for tight composition. I took advantage of the "headroom" of 4x5 and enlarged/cropped mercilessly with the easel to make an acceptable 8x10 from a third of one negative.