Quite collectible and fun ... and inexpensive to collect the vast majority of these. The Scott Specialized notes:
1518, the 6.3 cent coil, 129 different Bureau precancels used in 117 cities.
1614, the 7.7 cent coil, 160 different Bureau precancels used in 153 cities.
1615, the 7.9 cent coil, 109 different Bureau precancels used in 107 cities + two carrier rate.
1615C, the 8.4 cent coil, 144 different Bureau precancels used in 145 cities.
Here are some of the same cities as the original poster shared, but on cover to show some of the users:
Boulder, CO: Psychology Today
Pleasantville, NY: Prevention
Milford, CT: Fortune
Smithtown, NY: TIme
And the same towns used with other precancels/users:
Rutland, VT: message from Readers Digest on reverse side
Milford, CT: Time
and the 9 cent coil from Pleasantville, NY: Readers Digest, first class postcard.
All from $1 boxes, I think.
With these magazine publishers printing many titles, finding other publication titles for the same towns would not be unexpected. I also suspect many uses of these bulk rate coils will be from contract mail preparation companies with numerous return addresses for their various clients. One of the challenges is locating used copies (on or off cover) perfectly knifed down the perforation row by the affixer. Potential for lots of fun.