Well, I think we should do that only in the most extreme cases. Ones we absolutely KNOW we won't get back to. That have lost interest, or never gained interest in the first place.
Otherwise, why not simply put off on some until others are finished?
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)