VFO's for ham radio work would involve higher frequencies,
and I would think that they not drift anywhere as bad as
the AM radios did. I looked at a few tube VFO schematics, and
I don't see anything that different from the AM radio
hartley osc circuit. So how did they avoid drift, or were
you expected to leave your VFO on all the time?

Some VFO's e.g. in the BC221 use a compensation
coil, moved by a bi-metal, inside the tuning coil as temperature
compensation.

Wim