For sure the caution is well-advised.
It’s happened to me several times over the years: I hear great things about a particular flute-maker or pipe-maker, play several examples of their instruments which are uniformly good, put in my down payment to get on the wait list, wait a year or so for my instrument to come, and when it does it’s not anywhere near the quality of the numerous examples by the same maker I’d played in the past.
There was one pipemaker who I specifically told this to, how many times I’d got a chanter or flute from a maker of high reputation and it be a rather different than the several others from the same maker I’d tried. (One pipemaker told me “oh, on your chanter I thought I’d try a different bore just to see how it came out.”)
This guy assured me “no, I never change my design. I’ve settled on it, I know it works.” I believed him, because a friend has three chanters from that maker and they play identically, and a big-name player told me he has two chanters from that maker that play identically, so much so that at a performance he just grabs whichever one happens to be going a tad better that particular day.
But guess what? After a 2-year wait the chanter came and it wasn’t good. The friend who has three chanters from that maker, which he says all play identically and he can switch the reeds between them, came over and we could see that the chanter I got had its holes drilled in different places, and the bore was different enough that reeds that worked in the other three wouldn’t work in this one.
So no matter how much research you do, how many examples of a maker’s work you try, how much praise a maker gets from big-name players, you never know what you will get.
I will say that there are some makers which I’ve never encountered inconsistency with, for example Patrick Olwell and Michael Burke. I’ve probably played 30 or so instruments from each maker and they’ve been quite uniform. (I did play one not-great but very good flute from Olwell, one of his earliest efforts.)
I’ve never played a less-than-good Goldie or Sindt, but my sample size from those makers is small, only around 10 Sindts and only 2 or 3 Goldies.