When you are first starting out on forging a new routine, external accountability can be beneficial. Like meeting a friend at the gym on certain days of the week. If you don't show up, you get that phone call.
"Where are you?"
For writers, that external accountability can be used to help keep you on track with your self-imposed writing deadlines. Or it could be as simple as showing up for that write-in and buckling down to write.
However, there is a danger that accountability can shift to reliability.
Let's say that you've been going to the gym regularly with a particular friend, but that friend is going on holiday out of town. Are you the type of person who keeps going to the gym anyway, or do you find an excuse—any excuse—to not follow through on an established routine? If you're the one to find an excuse, then you have slipped into the realm of reliability.