Is there anything wrong with blowing a Shofar at night:
on Rosh HaShanah for the Mitzvah (or just because one missed it and wants to hear it, eg., the person was ill)
on Rosh HaShanah for practice
during Elul for the Minhag of hearing it daily (eg., they missed it)
during Elul for practice
any time of the year for some communal purpose (a ceremony, wedding, demonstration, etc.)
any time of the year for some personal purpose (practice, musical enjoyment, musical trick - hey look what I can do, teaching others to blow or just about the Shofar/R"H generally, etc.)?
Note that the question isn't "Is anything to be gained?".