Recently, while working on some large paintings on canvas I had an idea to transfer my subject matter from canvas to paper. The idea was an itch that I simply had to scratch and I couldn't continue with my other work until I had satisfied this new exploration. I made the work very small so I could explore iterations of my subject quite rapidly. Once I had the chance to work through that project I was able to return to my larger canvas works with full focus once again.
Often when I'm "in the groove" with my work it is common that creative floodgates will open and I will get an incoming barrage of OTHER great ideas. You know - the ideas that usually have nothing to do with the work you're creating and might even distract you from the task at hand. I have come to understand that these ideas need to be dealt with asap. I like to acknowledge them for a moment and then record the idea or work on it right away. I have spoken to many creatives who say that they have trouble finishing work or that they get disheartened part way through the process and I believe that this can sometimes be attributed to the issue of those incoming other great ideas.
Sometimes these ideas come in the form of doubting material choices:
1. I should have made it smaller
2. I want to use darker colours than this
3. Maybe canvas would have been a better choice than paper
These thought patterns can be constructive or they can be utterly paralyzing. By choosing materials carefully at the very start some of this "waffling" can be reduced. On the other hand these observations can help hone an idea or style in order to become more discriminating about the work you are creating.
What I like to do in the moment that I get the incoming/disruptive idea is jot the idea down in my planner - just a brief outline and go back to my painting session. Unless there is some possibility that I might actually be able to combine the idea with my current work - this doesn't always work but when it does it can lead to real innovation. With great risks come great rewards - but sometimes ruined artwork, hence the risk.