shlishi,
I didn’t say that. There’s an inyan to be consistent in the zmanim (even more so on the same day).
Englishman,
Yes, but it may be okay under certain circumstances. It should not be tarti d’sasri, meaning there should be a reasonable way of considering mincha during the day and ma’ariv at night (e.g. before/ after plag or shkia) and a sha’as had’chak, such as difficulty in organizing a minyan later. Otherwise, ma’ariv should be after tzeis hacochavim.