At Chabad last shabbos, having decided to attend there monthly. In the spirit of shabbos, I suppose, they start a little later than AKSE but finish a little later as well. It is their custom to have the ba-al tfiloh actually recite the full text of each psalm which makes the preliminary service longer but also gives me more of an incentive to read along and get more familiar with the Hebrew. Since they start later, I tend to arrive earlier in the service than I do when I attend my own shul but the flow of attendance there seems much like the flow of attendance anywhere with a few people there at the onset and a crest of the bell curve of arrival time just before Torah reading. The first Kaddish usually does not have the required ten men at either place but usually does at the official call to prayer, known as the Borechu. As I entered, I was #8, taking my usual place in the back table to the right of the men's aisle. Not much activity as the prayers moved along in their usual sequence. As we approached Borechu and the kaddish that precedes it, a high schooler arrived with his father to follow a minute or two later leaving us at exactly ten at the time our quorum was required, much like the Japanese "just in time" supply system that keeps their production efficient. Of the ten, eight generally attend weekly, one Hasid in a traditional attire was probably visiting one of the Rabbis, making me the more random attendee which enabled the service to move onto its desired sequence. By Amidah repetition there were a few more men, making the minyan secure.
So had I been someplace else that shabbat, their service might have been less than it could have been, at least for a few extra moments. By Torah reading, there were enough men in attendance to distribute the various honors, but for a few moments before that I was tacitly essential.