I also think it depends on the type of knives youre selling ,.. the 6-8 knives is usually high end folks, and all handmades that I see. Understandable, since its high dollar work, and can take months to acheive that many knives ,made at that level.
Guys who have the blanks cut,and do a lot of millwork ,and complete series of knives in batches can get a lot more made per show they attend. So you tend to see 15 and up from them. both have valid reasons for how they work it,.. and usually a diff kind of clientele as well,so it works for them.
I do agree that the "hold back' is a bad way to go. It not only makes folks angry because they feel a choice of a knife they may have prefered is denied them,.. it can also SEEM like bait n switch "I only make 12 knives a year"-- yet you keep having more knives on the table all thru the show. Looks bad , even if you dont intend it.
We all know how quickly people see the wrong thing these days ,and dont think it over before throwing a fit.
It only takes one angry guy,with a few memberships in various forums, to spread a ton of manure in an hour or three that can take you YEARS to wash off.
No one needs the hassle.