nice winding job,
"fill factor" is a spec that is sometimes used on winding prints,
it represents who tightly packed the turns are, there are many different fill factors possible on a precision winding machine, especially the old 60's machines with gear driven cams.
a layer can look like the turns are touching each other, but in reality, it is not feasible to wind coils this way on a multiple winding machine where you have 10 or 20 coils being wound at the same time.
allowing a little space between turns will mean that you will save crossovers on one or more coils due to wire tolerances playing havoc with the winding process, all wire varies a bit diameter wise as you un-spool it.
so if one coil's wire decides to run .0003" wider than it's next door neighbor, having a fill factor of say. 91% will allow plenty of room so that the thicker wire does not overlap itself.
with a single coil of larger size, you can hand wind it with a higher fill factor. as you simple hold the wire at a slight angle to the left if winding left to right so that the wire is actually rubbing up against itself . if the angle is too high, you have to stop and rewind the coil to undo any crossovers, this is where the art of winding comes into play, good winders can hear and feel the wire touch as it spools on the coil, too much vibration or noise means move the wire a bit faster to the right,
so you can get less leakage inductance with a hand wound coil. but you also have more capacitance. so fill factor can also be used to control capacitance between turns. however, out of all the capacitances you have in a coil, turn to turn capacitance is usually the least worried about. layer to layer capacitance plays a more important part in high frequency characteristics.