yes exactly. it would be a moving target. no consensus or ideal fit. it would require an indepth breakdown of each last by width at ball, heel, length, instep etc. and how each last last relates to one anotherf last is a good starting point no? does everyone (everyone with a regular instep, regular width) agree that a 45 f last is a 12 (uk11.5 EG and G&G, Alden Barrie 11.5)9 - 4210 - 4311 - 4412 - 45?