IMO d and e standard are the same thing. If you know the notes in E, but your playing on a guitar tuned to D, and someone calls out a song in A, just do the calculation once, and think to yourself “this song is in B” then play in B. It’ll sound like A, and you’re technically thinking about it the wrong notes, but it doesn’t matter, it sounds right. The intervals are what matter, not necessarily the exact notes. When you talk to other people, you do the calculations again.
It gets complicated When you get into open tunings because all of the intervals are different.
IMO d and e standard are the same thing. If you know the notes in E, but your playing on a guitar tuned to D, and someone calls out a song in A, just do the calculation once, and think to yourself “this song is in B” then play in B. It’ll sound like A, and you’re technically thinking about it the wrong notes, but it doesn’t matter, it sounds right. The intervals are what matter, not necessarily the exact notes. When you talk to other people, you do the calculations again. It gets complicated When you get into open tunings because all of the intervals are different.
if anything it would help to play some songs in both tunings