[radio1]

Do newly wrapped coils 'break in' or 'season' with age? I know it's a loaded question, but curious of others experiences.

[morzh]

From the electrical point of view this is a bunch of hooey.....all these break-ins, be it cables, coils.....

Over time your bobbin could absorb moisture and stop being a good bobbin. But this is degradation and not a break in.

A well-made inductance will change a little if not at all over time. Inductance is dictated by geometry only. If you designed it so that your geometry is stable, so will be your inductor.
And even then......moisture is your main enemy. It is conductive and counters the inductance by the eddy currents appearing in the moisture mixed with chemicals.

[John Bartley]

The basic answer?

No. There is no breakin period.

If you wrap a coil for "x" mh and you have done your job correctly, it will stay at that value until you change something about it.

[EdHolland]

I can imagine very small effects.. A change in Q factor or self capacitance might result through the drying of varnish or laquer. Whether this would be noticable in anything but the most sensitive tests and applications, I doubt very much.