Buying the same brand doesn't always work either though. I ordered two different pairs of size 9 Clarkes, and one was more like a size 8 when it turned up.
If you can't actually try stuff on in a shop then it's just pot luck.
I'm currently sitting on two pairs of clarks shoes I've just bought, one is a size 12 that feels a bit tight but I'm hoping will stretch a bit (canvas), the other is a size 12 that feels too big and i'm worried will rub like hell but is slightly smarter and more what I'd actually like.
It seems i'm basically anything from a standard 12 to a 13 wide depending on where, when and what shoe i'm buying which is really fun when no retailer stocks 12's or 13's in store routinely, and I cannot spend the time and energy to go around every retailer in say my local shopping centre asking the question and trying the rare and elusive size 12 on* (I've said it before but even the big clarks in MK doesn't seem to actually stock 12's on a regular basis, and the smaller or less specialised stores are basically no chance at all)..
I used to buy a specific type of clarks shoes that just fitted and they still sell (IIRC at one point it was one of two standard issue pairs for some RM staff), but it's smart leather shoe with little actual grip and a nightmare to try and drive in.
Ironically it's actually easier in my experience to get "Smart" and dress shoes than normal day to day ones.
Even the same product but in a different colour can sometimes be a totally different fit
Yup.
One of the reasons I tend to stick to M&S for jeans is because from what I can tell the QC in sizing is pretty good, and the sizes are fairly consistent so if you buy a pair of jeans and it fits you can buy the same pair (or in a different colour) a year later and be fairly sure it'll fit.
I used to buy some slightly cheaper ones from a couple of other retailers and it seemed that I had to check every pair for fit, even if I bought them a week apart as it seemed that every batch was different.
*I last did the rounds in about 2019 and spent an afternoon going to every shop in MK that sold casual shoes with a friend (who IIRC bought 3 pairs, the lucky sod is size 10), pretty much the only ones that I found in my size were some hideous trainers that looked like someone had stepped in unicorn vomit.