there are a load of these modules - not just the bastl and alm - doepfer, ime, etc etc
some pedals don't need them - moogerfoogers are generally ok with modular levels and my strymon mobius works fine with them - if you need a bit of a boost to get back in to the modular, some vcas (veils, for example) work perfectly well
one thing to note with guitar pedals is they often don't work that well with bass frequencies
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities