As a kid I was a perfectionist when it came to drawing. Five minutes into a drawing, if it didn't look EXACTLY how I wanted it to, I tore the paper up and started again. This habit lasted until high school, where my grade 10 art teacher Mr. Alspach told me I wasn't allowed to rip anymore pages out of my sketchbook. When I asked him why, he told me that I wouldn't be able to see any of the progress I made in my skill. I may not like the drawing, but I could learn from it at the very least. So I stopped ripping pages out of my sketchbook. Then the subjects had to look super realistic and I would get so frustrated if they didn't. If I was drawing buildings, I used a ruler. I hated drawing this way. It took all the fun out of it and still didn't help me to make the drawing look any better. I used a ruler on canvas to draw out straight lines for buildings up until 6 years ago. I was painting a cafe scene from a trip to Victoria I had taken, and decided on a whim NOT to use a ruler to make the buildings perfectly straight. I had done this a bit with drawings now, and they were wonky and interesting....and SO much fun to create and look at! So....why not take this theory to my painting? The buildings turned out slightly wonky, the perspective was not too bad and it turned out to be a great painting! About a month later, that painting was purchased by a group of teachers for one of their friend's as a retirement present. It now lives with the happy recipient somewhere in Toronto. She loved it, I loved painting it....and my rulers now get very little use. They also don't get any paint on them....which is also nice.
Needless to say, I don't worry about straight lines anymore. For me (at least) it takes the fun out of the work. I'm not a draftsman, no one is taking measurements of the buildings from my pieces (at least, I sure as heck hope not!), and the viewer can recognize the location of the subject if they are familiar with it.
I'm not saying lock your rulers up. I'm just saying sometimes it pays to think about what we really 'can't' do without when working on our creative projects....and try something new. Sometimes this is all the impetus you need to refresh your inspiration and begin creating on whole NEW tangents!
Better get on that, hmm?