I enjoy a few different styles of photography...
Wildlife - from land or from kayak...
Street - some people but mostly things and places...
Event - preferably candid as opposed to posed groups...
Flowers - from 'portrait style' to macro...
Macro - mostly of flower 'parts' and insects...
B-Roll...
Wait - isn't b-roll a "video" thing? Isn't b-roll that filler footage for videos?
Well... ... ... ... yes... typically.
But when I shoot an event I watch for those little side shots (I think maybe everyone does, yes?) -
...the row of wine glasses on the front table with the event logo and date etched into them that I notice out the corner of my eye while some speaker is talking at the microphone...
...the line of instruments on the ground at a band practice I happen across while the kids are taking a little break...
...the aligned tags or folders on the registration table that catches my attention during a lull in registration...
...the perfectly aligned leaves in a circle on the path as I look for that perfect wildlife shot...
The thing about b-roll is that they are the shots that sneak up on you... the shots that you just have to take because you saw them - even though you were there at that moment for a slightly different, or sometimes completely different, photographic purpose - purpose 'A', if you will.
They are purpose 'B' shots.
Shots you take because you can't NOT capture them...
They just refuse to NOT be captured.
So you take them...
And then you process them...
Sometimes they are just slightly off topic - related but just not your soul purpose for shooting that day...
And sometimes there is that one that I try to figure out how to catalogue so that I'll be able to find it again some day because it has nothing to do with the rest of the shots from the day - the shots for purpose 'A'. (if I counted correctly, shot 6 below is a great example of this)
They are the shots that just visually capture me and light that little creative fire and make me even hungrier for the next great purpose 'A' shot...
Sometimes they are shots that will probably never get used for any 'real' purpose as far as recording the event, but they are the shots that I pause at every time I go through the gallery of all the great (IMHO) purpose 'A' shots from my shoot - the ones that remind me of that moment...
The moment I saw them... captured them... and smiled.
Again, shot 6 (if I counted correctly) - I will always remember that shot and the little one sentence story that it tells to me every time I look at it.
Do you have any shots that appear in the middle of a shoot that are completely unrelated, out of the blue, but are still some of your favorites?
Below are some of my favorite recent band photo shoot purpose 'B', or B-Roll, captures...
snack break 'paraphernalia' abandoned during band practice...
a case silently awaiting its instrument during practice... literally declaring its lonely state - Soloist...
all paced with such care...
Instruments 'abandoned' on the field during a snack break...
two... side by side... one with music and seemingly sharing it with its partner...
so... many... saxophones...
two gold... one sliver... and a kazoo?
the one that would not stand...
I have so many of these b-shots. Sometimes I consider myself to be ADD because of those shots and because of those shots I can not get myself to purge my files, instead I fill out one external drive after another. Someday, maybe ..... 
I love this kind of shot - if I ever had to shoot a wedding or some other sort of social event, I'd probably be a total failure because I tend to prioritize these kinds of scenes over the main point of the event.
But you clearly did not miss the point with these, or your previous marching band posts. These are just icing on the cake!
Thanks! I do feel that a huge part of photography for me is that it has taught me to see details - the beautifully interrupted symmetry of the one glass slightly out of alignment with the other 30 that becomes another favorite photo of perfect imperfection...