The different deadlines these competitions set I find useful as a discipline for me. The competitions also tend to vary the word counts they require and that can be a good discipline too as I write to the different standards wanted.
I don't set a deadline as such for a novel given it is more complex than a short story but I do want to have a first draft written and typed up and a basic copy edit done in a year. I know there's still a lot more to do after that but I find it a good guidance. It stops me dragging the novel out. By the end of a year I've got something I can work with. I think my next stage is to set myself goals for one complete year - i.e. have so many stories out, have a draft novel written and so on - but to set targets and then meet them is a good habit and hope it stands me in good stead, hopefully for the day when my novels might be published.