[Avodah] tefillin on chol hamoed

[Isaac Balbin via Avodah]

[Micha:]
> And while I do not have an explicit source, it is implied by Nedarim
> 81b and the Ran ad loc who say that a minhag is a neder created through
> the mere action of performing it. Which derabbanan would be a binding
> neder. Similarly, the case we've revisited ad infinitum from Maqom
> sheNahagu (Pesachim 50b) is where the people of Baishan are apparently
> being told by R' Yochanan to follow minhagt because the parents did it.
> In Nefesh haRav, RHS cites R Moshe SOloveitchik saying that despite the
> above, the Rambam holds that breaking minhag is assur as perishah min
> hatzibur. A machloqes with the Ran, but still appears to be saying that
> a minhag is a minhag by virtue of common practice. Not formal enactment.

I wish I could recall the particular Minhag but Mori V'Rabbi Rav Hershel
Schachter did once pasken to me that a minhag that is simply Shtus,
has no status and one should abandon it as a mistake. In some cases
there could be issurim involved in keeping the minhag! This wasn't a
wide spread world accepted minhag.