Is it okay to improvise ingredients with crock pot recipes?

If the recipe calls for cooking it for 4-6 hours on high and you want to leave it for 8 then change the setting to low. If it calls for cooking it on low add more liquid, otherwise it will get dry and burn on the edges. Adding more ingredients is also okay. If you would prefer canned veges to frozen or fresh add them about 1/2 hour to an hour before you want to eat, if possible, otherwise they will pretty much dissolve.