Cut off wheels will explode if they are bound in a cut or subjected to side loads. The guy most subject to this is the guy who only has one 4" grinder and is in a hurry. Those small grinders are cheap enough to have more than one and each one with its own type of wheel on it. Plus it is a lot more convenient to have those little grinders available with the proper wheels for each type of grinding..
I have tried most all of it and now do what is known to work..