In my cong it seems to depend on who you are. For instance, there are some who are reaching out for MS or elder. Depending on who you are (and, I think, whether the PO likes you or not), you might be able to miss a meeting here and there without risk of losing the chance to be appointed. There are others, however, who will not be considered if they miss one meeting by the next CO visit.
Another example- There is a certain DF'd person who seems to think their chance of getting RI is pretty good despite this person's lack of attending ANY bookstudies and frequently missing the School/Service meetings and the Sunday AM meetings. The last time this person met with the elders, they just told them that they're doing good, just wait a little while longer! (This person committed SERIOUS sins over and over while concealing it for YEARS, hence the "wait a little longer"). Do the elders notice/care if this person misses meetings? Will this person's meeting attendance factor into their bid to be reinstated? Evidently not- cronyism at its best!
Yet another example- There is a man who is a racial minority and a single father of two young children who has struggled financially over the last few years but has attended meetings (comments, too), been through the Knowledge book, the require brochure, The Daniel book, the Worship book, and the Bible teach book. He told me that he has already made his personal dedication to Jah, but the elders keep declining to make him an unbaptized publisher because of his meeting attendance. THIS GUY HAS NOT MISSED ONE SINGLE MEETING SINCE MAY and missed very few before that! While this bothers the guy somewhat, he is still loyal to the org. Go figure!
I also had a conversation with an elder who is of the "annointed" once about MS and elder appointments. He said that there are some who just won't "cut it" as a MS, and he actually named a brother as an example! Quote; "Brother <so-and-so> will never be a ministerial servant". What a crappy thing to say about someone!!! Especially since this elder just moved to our cong a few months ago and doesn't really know anyone that well yet! It makes me wonder if he's just repeating what some of the other elders have said. The thing is, Brother <so-and-so> once WAS a MS years ago.
So I guess it just boils down to what the elders' agenda is. If they have a personal reason to notice your attendance, they will. Otherwise, you're just a number on the attendance count!