I used to work at a watch shop. When I was taught to size bracelets I was taught (by a professional watchmaker) to remove them evenly but if an odd number of links had to be removed the extra should be in the six o’clock side of the watch.
but, in the end everyone’s wrist and personal comfort are different so you do what the customer wants.
for myself I do it evenly unless it ends up uncomfortable when I’m done.