I have been working with TM/METAL data and some of my programs that process it, and decided to run the "edge length distribution" on tm-master.tmg. Lengths below in miles. Note that is a "collapsed" graph, so these are distances between visible waypoints, taking into account any shaping points along the connection between them.
Edge length distribution (exponential):
0.0 <= len < 0.125: 19167
0.125 <= len < 0.25: 30330
0.25 <= len < 0.5: 65020
0.5 <= len < 1.0: 121695
1.0 <= len < 2.0: 166518
2.0 <= len < 4.0: 140926
4.0 <= len < 8.0: 78753
8.0 <= len < 16.0: 19516
16.0 <= len < 32.0: 3988
32.0 <= len < 64.0: 997
64.0 <= len < 128.0: 167
128.0 <= len < 256.0: 13
Here's the top 20:
G7@ToS312 to G7@S315 via G7 length 225.8419
N3/N17/N17F to N17/N17C via N17 length 215.5958
A17/AH62/E123@Syu to A17/AH62/E123@ImeKom via AH62,A17,E123 length 211.0824
NL510@MusFal to NL510/NL516 via NL510 length 169.9347
NL500/NL510 to NL500@JohnCabSt via NL500 length 167.8178
G4213@S207 to G4213/G4213Fan@HB/SN via G4213 length 162.4528
G7@ToS312 to G7@S213 via G7 length 157.4454
AH42@ChaRd to AH42@YiLoc via AH42 length 150.4283
G7@NM/GS to G7@S214 via G7 length 150.3914
AH32@BayNuur to AH32@A22_W via AH32 length 148.6031
AH42@Tan to AH42@S308 via AH42 length 142.8158
RTR30@Rito to RTR30@EN160/295 via RTR30 length 131.3696
E003@R180_W to E003@Min via E003 length 131.0283
RTR46@S439 to RTR10@N4_E&RTR46@N3 via RTR46 length 123.5412
RTR105@EN190&RTR20@EN190/260 to RTR202@EN260&RTR20@EN180/260 via RTR20 length 123.5229
C5@WolHill to C5@TwinHilVlg via C5 length 123.3106
C16/N1/SW to B1/N1/SW@RobRd via N1,SW length 122.5820
N5/N17|ESH to N14_S/N17_S via N17 length 118.9905
RN19@RR101 to RN19@End via RN19 length 117.7725
N83@NapSt to N83/QLD62 via N83 length 117.7152