These threads seem to bring out common themes repeatedly.
1.) Many people on ScubaBoard believe the buddy system should entail routine practice of close proximity shoulder-to-shoulder or near equivalent diving with mutual situational & buddy awareness and frequent monitoring of the buddy, ready to intervene quickly in case of emergency.
2.) In the 'real world' of vacation diving, and even local diving for some, insta-buddies are a common fact of life and often won't adhere to such a system, and even regular buddies often won't, either. So, unless you haul your GUE-trained team around with you...(with a good natured nudge to TSandM...).
For the high-viz., often warm water tropical vacation diving a lot of people do, a more lax approach to the buddy system is obviously common (one thing I guess most all of us would agree on), and it's easier to go with the flow than try to impose your diving world view on a one-shot buddy. As some pointed out, many random insta-buddies are open to some buddy system practices; pre-dive gear check, staying closer to each other than the usual, etc... But a lot of people won't adhere to tight buddy procedure. You can follow closely beside the person if you wish, of course.
Yet the overwhelming majority of these people return from their dives without death or serious injury, and I imagine the majority had a good time.
I think a few factors impact people's attitude on this:
1.) Dive conditions - shallow tropical reef vs. deep diving a wreck in the Great Lakes.
2.) How you were trained - as Jim Lapenta pointed out, what your training suggested was & wasn't important, the values you incorporated early.
3.) Your personality - are you normally a situationally aware, team-focused person who likes engaging and adhering to formal standard practices (e.g.: 'rules')? Or are you a more laid back sort who's more casual in your approach?
4.) Your attitude toward risk. Example: Say you were to crunch the numbers and discovered that on a given dive the way most people buddy, your risk of death or serious injury was 1 in 100,000, but if you dove TS&M's GUE team way, it dropped to 1 in 1,000,000. If that were the only issue, would you say 'Oh, well, that's different,' and change your dive style? Or would you say '1 in 100,000 ain't bad' and accept that risk as the cost of doing things your way?
5.) Your attitude toward de facto social norms. Even if you believe all buddy teams ought to be diving the formal way some purists on the forum endorse, when you get on a dive boat, you can either 'When in Rome, do like the Romans,' or compromise - talk it up with the insta-buddy and accept some crude improvements, like a rough pre-dive plan, hand signal review & plan to stay close together, or take the option to be a 'crusader for change' - you're going to school that insta-buddy on how this buddy dive is going to be done!
Personally, on warm tropical dives with good viz., I try to stick close to...the guide. That's the person who knows the route & will get back on the boat at the end of the dive. If I'm with the guide, so will I. If I am assigned an insta-buddy, which I don't ask for but when in Rome, he/she is welcome to stick with me.
Richard.
P.S.: File under all or nothing, black or white thinking - I notice a tendency to divide buddy diving into 2 groups; formally compliant excellent buddy procedure pairs, and 'might as well be solo diving' pairs, with a denial of shades of grey. If I'm diving single tank with no pony at 90 feet going around the far side of the Hilma Hooker wreck in Bonaire, and my gas supply somehow gets cut off, I would rather have a buddy 20 feet away than no buddy at all. Even if a bad buddy only offers 30% of the risk mitigation of a good buddy, that's still something.