Yes, we can tweak the settings on our mouse so that the interval between the first and second click of a double click is perhaps a bit more suited to an older person's hand, but there's a limit to how much this can be done. What's more, the times at which a double click is called for, or when a single click is sufficient, though clear and logical to experienced users, aren't particularly obvious to new and hesitant users. This confusion often leads to a double click that activates something that shouldn't have been activated, or to a single click that, not having generated any action, is followed by some other mouse activity - usually taken out of desperation, rather than with any clear intent, and in the end, predictably counter-productive, or at best simply unproductive.