THIS! Make sure you are utilizing all the little "tricks" of whatever program you are using. Like with CSP, it is wonderful for buildings since you can just draw one line straight down, several lines across, and then use the vector eraser to erase the extra lines in between. You just have to make sure you are using a vector layer. I use vector layers for backgrounds and word bubbles and raster for most other layers.
Also try gesture drawing to help improve drawing speed. Draw a pose in 5s, 10s, etc to help get used to drawing more quickly.
Try 24 hour comic day too as a challenge! Draw a 24 page comic in 24 hours!