You know, I once encountered this issue when
I tried to make a rip of Neo Turf Master, and I soon dismissed it because of my proverbial lazyness. A
Neo Turf Master pack was created by someone else eventually, with overabundant loops, e.g. the actual loop in the VGM file is actually the second loop of the song, while the first loop is all treated as introduction. That made me think about a
different approach: since (at least in Neo Turf Master) the channel layout doesn't change anymore after the second loop, it might be worth to hex edit the first loop to use the "correct" instruments from the starts, to properly trim the loop in the VGM file itself. Of course this isn't always true for other songs, which might have different instruments in every subsequent loop, but it wouldn't require any edit to the VGM standard, such as new commands, it would only require a new tool which would "cheat" and "fix" the first loop. The caveat here is that both our ideas would alter the VGM data, going against the spirit of preservation which should be behind it in the first place. Still, brainstorming!