My Gulp tasks are fine tuned for my site because I have thousands of posts and found it painfully slow to make simple CSS changes in development quickly.
So, what I have going is a crazy set of tasks that do all the asset work (preprocessing, minifying, concatenation, optimization, etc.) in a temp folder that Jekyll doesn’t watch. So I can make CSS and JS adjustments quickly and see them live in browser instantly with Browserify without triggering a slow Jekyll build.
Then there are build and serve tasks that essentially execute the normal jekyll serve and build commands with some production flags depending on if they’re preping for a deployment or not.
I also have some tasks that copy thousands of image assets between temp and prod folders to keep them out of the Jekyll build process as well. I found it quicker to shuffle them around with Gulp than Jekyll since at my scale it was slowing the build time down.