As you acquire properties, it's almost never possible to rebuild the systems from scratch, and instead it's becomes layers upon layers of patches and quick fixes.

A fun one lately has been AT&T. We have streaming with DirecTV, and they of course share authentication with the parent AT&T. So whenever I try to login to AT&T's website to manage my wireless or fiber, it redirects and logs me into DirecTV, everytime. The only way I can manage my service is to use AT&T's mobile app.

AT&T has the worst/buggiest login process I've encountered, and I also have to use Comcast/Xfinity.

Logging in to pay AT&T wireless service sometimes takes half an hour of attempts resulting in any number of weird errors until it just works.