Would it be unessacary to run more than 6 miles on my distance days?

Ok Im on the track team and I run the 800 and the mile I'm trying to get a sub 5 min mile. My curren time pr is 5:03. And now I'm doing 6 miles on my distance days and repeat 100m on my speed das, would it be pointless to run more miles on my distance days? I think it would be different if I ran the 3200....BUT I DONT. the mile is the longest event I do. So would increasing my miles be pointless and useless or benificial. Explain your answer THANKS :)