Have you built a .deb with debuild and debhelpers? Can you recall all the goofy rules about what needs to go in each file and what each debhelper does? How do you keep all of it in version control and build downstream packages that depend on the changed one? Have you managed to accidently sneak a local build machine dependency or piece of information by accident into the final .deb only to realize it much later?

I found it be a big ball of easily forgettable twine of rules tools and oddities myself that every time I needed to redo something was a hassle. With many foot guns that lead to odd package issues.