at 5’8 i have almost all of my blazers shortened - i think it helps with the proportions and avoids calling unnecessary attention to your mid thigh. it normally not too much of an issue but as i get more and more particular regarding the details of blazers i’m finding its becoming a real hunt for an off the rack perfect fit.
that being said, i’ve had luck with:
bonobos - i bought the alma mater blazer a few years ago and to this day, the fit is awesome. they may have changed their fit over the years but the 36R worked great for me.
club monaco’s XS - while i think the sleeve measurements occasionally need a bit more scaling when sizing down to XS the length on club monaco’s XS blazer fit is pretty great. i have some true standout & standby piece rom club monaco and they’re always strong with the basics.
j.crew’s XS fit - recently picked up a linen piece from j.crew and the length is pretty spot on. i could go a touch shorter for casual wear (t shirts, polos, summer nonsense) but thats only because i’m growing picky.
if you’re looking to get into more specifics - shoot me an email. firstname.lastname@example.org