asking this general question primarily for a touring bike build.
I don't weigh much, 140lbs, so don't put out much torque, and my knees and legs prefer a faster cadence now at over 50 as when I was 25, so I imagine this helps with bb's just like it does with all drivetrain wear/life.
Are there big differences in ext bb life from one type of ext to another? Just as there is with varying qualities of square tapers? Like I mentioned, this Hollowtech ll is used on those trekking cranksets.
I got 24,000km out of my first external bearing bottom bracket before it got a little rough; but it spent nearly its entire life with too much preload (FSA made some carbon cranks too narrow for the "correct" bottom brackets which come in several widths). For over half that time I weighed under 140 pounds, but was 205 at the beginning.
I don't think that was out of line with my last square taper bottom bracket, but wasn't using a bike computer at that time.
Some external bearing bottom brackets are sensitive to how the shell has been faced, wearing quickly when the left and right sides aren't parallel and co-axial.