Another voice:
{ID} is just for
bookkeeping (ooo, a pun
)
You may need ID if you are using the CLI. The CLI also has tools to
return the ID from other CLI activities so there is little reason to actually be IN the folder.
You may want ID for device file (duplicate?) management
Calibre reports 2books on device, having {ID} at the end of the template may help.
As for
Gaps, so what. This is not {Series_index}, where a gap means another book to buy
