The local shops keep their dated bread for me, which I allow to dry for a day or two but not completely. I then liquidise it and place it in a basin, usually at the back of my TV, where it's warm but not hot. After a day or two, it's bone dry. I'll add coconut, turmeric, milkshake powder, liquidised fish pellet, crushed hemp...all kinds of stuff.
I'm completely happy using my own groundbait but now and again I'll add a bag of shop-bought stuff to it. lately I've put SwimStim, Sensas Gold, Nutrabaits Carp Method, Sensas Explosive Feeder in it.
Whatever goes in it, it all gets mixed in and I just keep a big mix in the one tub and use it for everything because it should appeal to most species on one level or another.