Finishing a bad track provides irreplaceable practice in completion that starting but not finishing does not
The skill of finishing a track is a separate, practisable skill from the skills of sound design, rhythm programming, or composition. Abandoning tracks when they seem bad deprives the producer of opportunities to practise exactly the stages where finishing is hardest. Forcing completion — even of tracks judged hopeless — builds the muscle of closure. The finished-but-bad track has value: it goes into the scraps folder for parts, it may later be judged better than it seemed, and it adds a completed session to the portfolio of finishing experience. Failing more, and failing more completely, is a prerequisite for finishing well.
Examples
A track that seems hopeless at 80% completion is finished anyway. The final 20% practises arranging endings, exporting, and evaluating a complete work. The track goes into the scraps folder. Elements are reused in the next track.
Assessment
Identify one abandoned project that is more than 50% complete. Set a deadline (one week) to finish it, regardless of quality. Export it. Put it in the scraps folder. Describe what you learned about finishing from completing it.