A computer software system is like a house. You need to keep it in good repair.
From time to time, surfaces should be dusted and polished, and you have to put stuff away after you use it. You’d better know the difference between the kitchen room and the garage, and you need to remember to take out the trash.
If you don’t keep your software project in good shape, eventually stuff starts piling up in the corners, and you find yourself stepping over things without quite remembering what they are. Eventually, you might find it easier to just move out.
But with a little bit of tidying up and software maintenance, it never needs to come to that.