I've never received a premium for having the shoulders
Usually true.
The great thing about this hobby is that there's almost always exceptions to every rule! I've always enjoyed observing what people collect (even if it meant I couldn't afford to collect them myself!)
A lot of people assume that collecting consecutives would make shoulder notes have a premium and usually this isn't the case. So consecutives only become a premium in the
hard to find prefixes or
hard to find notes (where scarcity is a factor). Therefore consecutives might be highly sought after for change-overs, short prefixes, or error notes.
The kinds of consecutives most collectors are after are: Dominions, 35's, 37 Osbornes, 37 change-overs, 54/70's asterisks, DF's, X notes, and the like.
So when it comes to radars when are consecutives highly collectible? The answer I would think is: when it might involve a special serial number on top of the radar.
For example: 9999999, 1000000, 1000001
and occassionaly: 1212121 , 1212122, 1212123 (because of the 1-2-3 pattern) OR 4333333, 4333334, 4333335 (for similar reasons). Most radar collectors are looking for symmetrical or special number combos.
So shoulders of radars hold a premium when
the shoulders themselves are interesting special numbers, symmetrical, or hold a patternThis is what I've observed over the years....