When are GITHUB_SUBMODULES really worth having?

[Mayuresh <mayuresh%acm.org@localhost>]

When creating wip/OpenROAD (ongoing) I just followed the suit of other
package managers, including FreeBSD ports by adding packages like OpenSTA
and abc as GITHUB_SUBMODULES.

But I realized, making them separate wip packages was really much more
modular and convenient, taking out some unnecessary complexity and time of
developing the parent package.

Wonder if there are any guidelines about when to use GITHUB_SUBMODULES as
against making submodules a separate package. Could such guidelines be
added to the documentation?

-- 
Mayuresh