I have a crockpot recipe for burritos, located here, that I really want to make. It says to cook the mixture on low heat for 6-10 hours but that is too long/short. I really want to convert the recipe to a high heat so I can cook it quicker. Do you think it is possible to cook this on high? If so would the recipe itself change and how (more/less water required)? How long should I cook it on high?
You can probably get away with high heat, but you need to watch the liquid content. Since you're not cooking something that is liquid and can circulate to heat evenly, you risk burning the food or having it dry out.
I can't see any reason this needs to cook for such a long time. Ground beef is finely divided, so cooking for extended times won't benefit it that much. I'd say bring it to a boil either on high in the crock pot or on the stove, then transfer to the crockpot for 2+ hours (as long as you have).
At high you can cook this for 3 hours. For food safety the key is to get over 140F and up to 160 for ground beef. In my experience with the slow cooker I use, what I recommend will work; but there is variation with slow cookers.
And so you have a reference, according to About.com, One hour on HIGH is equal to two hours on LOW.