I guess you either can get good at cutting dovetails, or you can get good at patching up mistakes. Do better on the former and you don't have to do quite as well on the latter. Leave it to say I've gotten very good at fixing boo-boos, and am still working at making my touch-up and repair skills unnecessary.
David, long ago I got in the habit of saving the waste from cutting out dovetails for the purpose of having matching grain when filling the gaps.
Now that my dovetail cutting has improved, the scraps are still saved and often find a use in other areas.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)