First, in the simplist perspective, honing extensively over time is easier than all at once. The edge may get sharper in some sections or have small issues. These usually aren't problems unless you are trying to solve them under time pressure. Than, many times, you choose the wrong corrective action, when something much more effective would have been better. Slower, certainly. Although a shave test is a good indicator of the quality of an edge, 10 shave tests, followed by pre-shave stropping, is a more reliable and accurate assessment.
Second, I think it just takes time to get to know a razor. Even after they have been honed that doesn't mean that you have found the answer for how that razor needs to be honed so that it keeps an edge indefitely.
Another point is that stropping sets up the edge, which can mean that the razor seems to need to be rehoned again. With extensive stropping you've reset the edge slightly, so then re-honing allows a compensation of the edge that is already in place. You'll notice occasionally someone point out that they pushed through a honing session by stropping in the midst of the honing session. I don't know what this does, only that it can help.
It seems weird, but if you think about it, honing the razor and saying "it's done" without doing extensive stropping and shaving doesn't really make any sense either.
The most common example I can give you is the guy who shaves with a razor once and decides that it's too rough/sharp. Or, the guy who says the razor is too dull at the first shave. Both of these situations can be cured with extensive stropping. So if you give yourself a few shaves, maybe 10 to continue tweeking the edge and continue stropping as you go you'll start to get a better sense of what the razor should be behaving like. Too many guys just keep on honing, and honing, and honing, never realizing that the real problem is the way the edge feels after honing.