X Axis: Successful, active, energetic, busy
Y Axis: How frequently the person is late
End result: Unsuccessful people are late for meetings, cancel, miss them, etc, frequently because they're disorganized, sloppy, etc. As you get to the middle of the curve and moderate/large success, people don't miss meetings or be late. Being late and disorganized is hugely negative correlated with success.
But here's the interesting question: Why does the frequency of lateness/cancellations go up on the high end of the curve again? I don't personally think that successful people are less conscientious; all of my experience shows the opposite, by and large. It's a popular media narrative, but seems largely unwarranted and untrue.
What is true is that people who are doing important and large-scale things will wind up with events that are orders of magnitude more important than whatever is scheduled, and thus really justifiably need to cancel. I had a good friend who is clockwork-on-time shoot me a message a few minutes before we were set to talk that he had to cancel because he had an important investor want to fund 25% of their target for a Series A round. Yeah, dude, no worries. Kill it.
Y'know?
As people tend to use their resources well, they come into more resources and more authority. This means also, sadly, when things go wrong it tends to get kicked to someone that can figure it out well. Thus, crisis mode knocks out the successful person as well.
And a final key point -- young, ambitious, successful people tend to maximize their commitments and don't schedule downtime or contingency-plan very well. They focus on upside and doing more. Thus, when something inevitably goes wrong -- illness, a death in the family, or just a week of very high fatigue -- they literally have no slack to absorb things going wrong. If you're scheduled and performing at 90% of your maximum capacity and you miss a single week, it takes... 10 weeks to get caught up if you absorb that remaining 10%, and don't cancel anything or improve dramatically in your ability to process.
That's the paradox: especially true in young people who don't contingency-plan well, they're constantly behind schedule and playing catch up. You could do some math here and illustrate it, but the basic idea holds: the more you're scheduled close to max capacity, the longer it takes to recover from a down week. Then simply plug in how often you get hit with a down week (even the freakishly amazingly consistent top performers I know have a couple down weeks a year), and you've got a recipe for chaos.
What gets cut when chaos breaks out? Rest, relaxation, social engagements, etc. Which increases the chances of things going wrong.
A solution? Well, if you want your calls taken, clear-business-driven calls get canceled far less than casual social engagements. I find calls/appointments scheduled with a tight, actionable, very profitable agenda much more rarely get waxed and get rescheduled faster. But that's besides the point, you'll always have speculative and social calls if you're taking the introductions you've given.
How about on the other side? It's tough, because most driven young people want to be playing a high-risk high-upside game. The idea of lowering risk/variance to stabilize at a higher value of total outcome doesn't really appeal, because everyone successful/driven while young thinks they're particularly special (which may be true) and thinks that normal statistics and occurrences don't happen to them (which is certainly false).
Thus, you wind up with erratic and pendulum-swinging performance, and a few people who stack up huge successes through that mix of killer work ethic and not-too-much negative convergence at the same time (negative convergences of events can break even the strongest of people -- there is no worthwhile theoretical argument here; once you've seen it, it becomes indisputable). But the high-variance strategies have high-variance outcomes, leading to many people overwhelmed/overscheduled/amidst-chaos with the slightest of negative convergence.
This might be a large and largely unheralded reason why driven and talented people succeed less in their 20's than they could... sure, everyone has a few blindspots that only get exposed by pushing hard towards success and getting derailed by an error or gap in knowledge. But also, it seems like a lot of people build more sustainable and flexible schedules in their 30's, and lever that to huge success in that decade of life.
Sustainable and consistent outputs and performance improvements straight-up dominate erratic and inconsistent output and improvements. It never seems like that's the case, in theory, but it almost never fails to be true either.