The Permissibility of Varying the Opening Supplications

The Shaykh : But should I restrict myself to one of them, or should I say this one at one time and that one at another? We say: say this one at one time and that one at another. This is a rule that a student of knowledge should understand, which is that acts of worship transmitted in multiple forms should be performed by a person in all those forms, sometimes in this way and sometimes in that way.