Inspiration is what an artist thrives on. It's exciting to have an idea and be eager to run with it. It's important to work on things while they're fresh but you can run into trouble when you're hurrying and get impatient.
It's a common thing among artists...you can't wait until the paint is completely dry and lift a little of the last layer off, you get involved and end up smudging your graphite and lose the white of your page or you pop a piece in the kiln before its quite dry. The difference between great and average work can lie in the fact that an artist wasn't patient enough at some stage of the creation process.
Sometimes you can rework a piece and fix your errors but it's important to have flow, so over-working is never a good thing. It may be better to re-think the problem and approach it from a new direction. This is where intuition comes in. There's a saying if you do the same thing over and over again you can't expect a different result. So approach things from a new direction...usually your work will give you a clue for the solution and creativity can take over...sometimes it leads to a better overall cohesiveness.
Most importantly don't box yourself in with thinking a piece has to be exactly what it started out to be...the act of creation is an on-going process, leave your mind open to the possibilities and use things to your advantage. Trust your instincts.
Strange note....Grasshoppers use spit!!!! Yep, saw it myself when looking at a giant one crawling up my picture window. It seemed to get stuck with no traction...so it stuck its front feet (?) in it's mouth and took a couple more steps til it got stuck again and repeated the action. So you got it here first folks, grasshoppers use spit!