How long do custom shoes last?

[NHAero]

I have a pair of Luck shoes that I bought virtually new from a Paceliner in late 2019. They were custom for him. Since the left was larger than the right, I took a chance and bought them, hoping that the larger left shoe would accommodate the carbon fiber AFO brace I wear due to nerve damage and lost muscle function in my lower left leg. hey fit well enough that I've used them now for coming up on 5 years and over 21,000 miles. The only disadvantage is that they use Atop instead of Boa closures so parts are harder to get (I ended up buying spares from Aliexpress!).

They still look surprisingly good, the leather must be good quality and the construction quite good. I'd be pretty bummed if they suddenly fell apart though, so I'm thinking maybe it's time to get a backup pair made for me specifically. They appear to be surprisingly affordable - the highest cost shown on their site is 299 Euros.

These are MTB shoes because I use Eggbeaters on all my road and all road bikes.

Thoughts?