I have the subjective experience of free will but also observe the following: it does not seem to be possible to plan ahead and make a willful decision as to what one's exact thoughts shall be in 5 minutes (or even 1 minute). By then one may still be involved in a certain overall task (such as reading a book), but what specifically will go through one's mind by that instance (whether a philosophic thought about free will or a thought about dishes in the sink) cannot be predicted or planned with any precision or reliability. Such future thoughts seem to be much more determined by external events outside one's control (e.g. the phone ringing) or other thoughts that immediately precede them. Hence freely choosing one's exact thoughts may be an illusion, and since conscious actions follow from thoughts these may also be more stringently determined that we like to think.
So here is my question: is this kind of thought experiment indeed relevant to the philosophical question of free will and if so, have such arguments been pursued in greater detail elsewhere in the literature?