I have checked a bunch of other forums and have not found a definite answer to my query.
Considering using schema.org/openingHours and wondering if the LocalBusiness schema (schema.org/LocalBusiness) must be in the code as a mother schema to make the use of OpeningHours valid and correct implementation.
Since OpeningHours is a sub-type of LocalBusiness.
I'm guessing the concern might be that using LocalBusiness schema as the mother schema might classify the site as local, which might limit international (or even statewide or national) rankings. @cricketer... is this the case? I'm assuming that there is a local office, though, as why else or how else could you post opening hours?
I've had sites with international rankings that did have local offices... and I put in a fair amount of effort to separate the local office and the rest of the site in terms of internal linking, and also conceptually. In each case, we used a local number for the local office and a different 800 number on the rest of the site... kept the local address in graphics on the international pages... and had a separate business name for the local office. This all was linked to from the Contact Us page, and we shared some articles and business offers, and that was it. We didn't have schema then, but I would have kept that separated that as well.
I don't know if this is the concern, but that's my guess. It's not uncommon for local businesses to spawn wider-audience online enterprises.
If the home page of the site is the home page of both the local business and the wider area business, then that's another matter. I'm seeing local businesses getting smarter and putting hours right on the home page... but those are local-only sites. I don't know what I'd do in that case, but I would be concerned about it.