Interestingly, once we analyze the historical cases, interesting observations can be made about them. In general, all the major historical cases of wide military recruitment of women usually boil down to "a female soldier, even if not as good as a male soldier would be, is still much better than no soldier". Countries in desperate wars for survival, garrisons in ancient societies that have levied all the men they could spare already, reserve forces, militias, nomadic peoples that drag their whole population with them so may aswell turn it into a numerical advantage on the battlefield....In the Sukothai period in Thailand extensive bodies of women were used as reserve pike units because while women were not as strong as men and could not fight as long, well-rested reserves committed at the critical moment could often win a battle even if qualitatively weaker on a soldier for soldier basis, and it allowed them to have greater numbers of troops than their enemies who did not employ women.
Of course, steppe nomads from the Aryan peoples in pre-modern times we continue to find evidence for higher and higher numbers of women under arms, possibly as much as one third of the mounted warriors. Herodotus has been right about almost everything else at this point, if Troy was real why isn't Themiscyra?
It's distinctly different from modern small, professional militaries that are under circumstances where they can pick and choose among reasonably healthy and willing men for their ranks.
Interestingly enough, the circumstances listed also tend to solve or alleviate any problems that may come with it - for example, a country in a desperate war for survival won't fret over what percentage of officers are female or some allegations of improper relationships in some unit that's currently getting shelled by the enemy, while a local garrison unit can adapt facilities without much cost, if any, and doesn't need top physical shape for long marches with days worth of supplies form their soldiers either.