A poster on the Worrisome Reasonless Xenogolf forum website with the member name of drumdude96 wants to know why graphite shaft manufacturers seem to be making shafts with larger and larger butt diameters these days, and that anything much over a butt diameter of .600 (inches) feels too big to the member. Three other forum members initially responded, all with pretty clueless answers. And their specific names are really not worth mentioning here. But what is worth mentioning is that combined, more than 38,000 posts have been made to date by these three respondents on the noted golf forum, and I cannot help but wonder how many people might have abandoned the game due to some of the responses given by these three individuals since they started posting. Solidly supporting my comments that many if not most so-called clubfitting experts associated with the noted golf forum website and other golf information outlets have no idea what they are talking about regarding many very basic clubfitting (and swinging) topics, I will provide a legitimate and useful reply here.
As clubs get lighter and lighter in general (largely influenced by lighter and lighter golf shafts), you will generally need larger and larger golf grip sizes to make your best swings. This is extremely elementary clubfitting knowledge that is not really difficult to learn if you just do the swinging you should be doing in testing different grip sizes on different weight shafts (which is pretty basic stuff). While not always successful at it (and perhaps some do not try at all), shaft manufacturers should broadly try to take this into account so that (ideally) if you install the same core size grip (that you believe is a good fit for you) on a lighter-shafted club as you do on a heavier-shafted club, then you should be able to swing two such clubs comparatively the same even if their finished grip diameters are different. (I note here that the same principles apply to longer clubs also).
Yet as fundamental as this is, it is not something that can ever be learned when fitting your golf grip size using the standard but loony grip-on-a-stick method or the even loonier comfort method of fitting your grip size and then just automatically trying to keep the determined size the same on all of your clubs. Fitting your golf grip size based on your hand size is fitting your golf grip size based on your hand size, no more and no less. Do not read anything else into this that does not belong. And fitting your golf grip size based on your comfort level at address or elsewhere in the course of a swing is fitting your golf grip size based on your comfort, no more and no less. Do not read anything else into this that does not belong. If done, do not complain to anyone that you feel you are not swinging your very best, because it was chosen to fit your grip size based on one of these incompetent methods (unless your complaint is directed at the clubfitting entity that fit your golf grip size [one of the most important club specifications there is] in such a manner). This alone quite commonly renders a clubfitting process somewhat worthless even if other elements of the process are executed well.
But if you want to fit your grip size in accordance with the way you actually swing, then you need to actually swing with different grip sizes on your clubs and compare them regarding how well you actually swing (duh). (If not sufficiently skilled to do that, then going by ball travel results would be the next best thing, although that can be more problematic). This can be a rather labor-intensive process and I am afraid there is really no shortcut. There are many, many times where at address the grip sizes among different clubs might feel (and might be) quite different and even uncomfortable. But in the end the only thing that really matters is that I am able to make my best swings with the clubs and that the best grip sizes are on each of the clubs to enable me to do that. Provided that I swing decently, I will generally become used to and comfortable with the grip sizes pretty quickly, even if they happen to vary throughout the set. Each of these particular methods of fitting golf grip size requires different levels of knowledge, skill, and/or effort in the areas of clubfitting and/or golf swing performance and will commonly result in drastically different levels of clubfitting and/or swinging success (or failure).
(The connotation of the term “set” might lead one to believe that all of the grip sizes within a set are and/or should be the same, and this was indeed largely true back when the shaft weights throughout a set were also basically the same. But this can no longer be considered a truism, standard, and/or prudent goal to pursue, as the very same golfer might for instance need a standard grip size on his or her irons and yet potentially a midsized grip on a driver having a lightweight shaft in order to swing his or her best among all of the clubs).
The bottom line is that you should not automatically dismiss (and “stay away from” to quote you) shafts having larger butt sizes. While it might feel like a jumbo-sized grip to you at address, there is a reasonable chance that you will actually swing it considerably better than if the shaft butt were more simply made to a .600 diameter that you desire. There are undoubtedly some good people in golf despite the overall horrific performance record and reputation of the clubfitting trade. You apparently have a ways to go regarding your understandings of golf swing performance and/or clubfitting, and one of the best things you can do for yourself is to not take too seriously the responses you get on the noted and similar golf forums. Most of the so-called “experts” on these sites are anything but, considerably contributing to the decline of the game as a whole in recent times. Find yourself a qualified clubfitting consultant as necessary or you might soon be persuaded to leave the game like so many others have in recent times (and with good reason). Good luck.