The problem with metronome markings, when put there by the composer or transcriber, is that they usually figure out the marking by thinking the music in their head and then match that to the metronome. They rarely figure out those tempos from actually sitting at the instrument and playing, or better yet, listening to someone else play the piece, adjusting the tempo to the speed they feel is right, and then matching that to the metronome. And we always hear music in our head faster then we would actually play it. The composer Daniel Pinkham told me that many years ago, and I think it is true.
When I was a student, I labored endlessly to play whatever piece I was working on at the speed indicated by the metronome marking, and thought I was a huge failure if I just couldn’t pull it off. When I got back to playing again after a hiatus of more than 20 years, I decided to ignore all metronome markings and let the piece find it’s own tempo. When I get a piece to performance level, I’ll occasionally compare what I am doing to the metronome markings. About half the time I’m doing exactly what the composer or arranger indicated. The rest of the time I’m a bit slower. In either case, i don’t care if it sounds the way I want it to sound.