"He sings with them Tuesdays and Thursdays."
Translation:Han synger med dem tirsdage og torsdage.
This is wrong. When you usually do something, then you have to add "Om" . Fx. Han synger sammen med dem om tirsdagen og torsdagen
That's exactly what I typed out. My Danish is still pretty bad, but this seemed most grammatically comfortable to me?
No, it's correct alright. In this instance you don't add the 'om', if you do, it makes the sentence sound more forced.
"On" is not used in the English version, which is a very good indicator that it ("om") should not be used in the Danish as well. Also the weekdays in English are plural, if you write "om tirsdagen og torsdagen", the weekdays will become singular. "Han synger med dem tirsdage og torsdage", is correct.
Why isn't it om tirsdagen og torsdagen? I thought that that is what you put for the habitual.
Because it is plural.
English sentence is incorrect. It should be "He sings with them on Tuesdays and Thursdays" or "He sings with them all (day) Tuesday and Thursday". Otherwise it does not make sense.