Display total performances for all the concerts you attended
Would users like to also see the total number of performances?
For example, you go to concert 1 and see bands A, B & C, concert 2 and see bands A, B & D and concert 3 and see bands A, C & E. Currently we see 3 concerts and 5 bands on our Overview page. I'm suggesting the page also displays '9 performances', which is a total count of all the 'bands seen' checkboxes ticked for all of your concerts.
I think this would be a relatively easy enhancement to implement, given the data is already captured for each concert that is attended by a user.