frozen roast in crockpot?

I think I saw a recipe on this site for using a frozen beef roast in the crockpot. How much longer does it need to be cooked?

What size roast would you cook like this?

What is your favorite cut of roast to use frozen in the crock pot?

I do this also … matter of fact got a couple of them in the crock pots right now … like you I have the older crock pots my DH had become very talented at fixing them … I have 4 that served me for years