I think there should be a more defined definition between batman and detective comics. Confidential has been pretty much defined like legends of the dark knight (from my understanding) rotating creative teams every 3-5 issue arcs.
Anyway, how about the idea detective comics is just batman up against joker riddler and two-face and more realistic villains, batman he's with robin and the bat family and other DC heroes against the more super powered villains.
I'm not too worried if people get runs disrupted by crossovers, as long as those crossovers (i.e. batman/detective comics) are written by the same person, or the current writers on each title write the story collectively. and it's collected in a tpb of that story. It's usually done to get an important story arc out quickly.
I don't like that in the second Alan Moore WildCats book you suddenly get two issues from "fire from heaven" a stupidly big crossover, which i haven't read but seems like it would be quite incoherent. They should've skipped those issues out and collected them in a "fire from heaven" tpb (ok maybe they did collect FFH but there's still 2 stray issues where i have no idea what's going on). But yeah I want to read them cuz they're alan moore, which is why i think he either should've been on a team of writers who collectively wrote FFH, or they got someone else to write those two issues and I wouldn't feel all completist...but that was many years ago, I don't think there are lots of examples I can think of..maybe between superman and action comics pre-IC, but I haven't read that many of them.