For me, at least, "maai" basically translates directly to something like "the matching of one's interval(s)." In essence, "maai" is the awareness and understanding of the relationship between distance/positioning and timing.
I know that some folks out there describe maai as that distance between you and your partner when your partner (or yourself) has to take a step forward to attack/connect. To me, that's just one aspect of maai.
I don't think there's one "correct maai" or anything like that as the situation mandates a different sense of maai. Just as you can't define the length of a piece of string, I don't think you can define "correct maai" as being, say, seven feet, three-and-a-quarter inches. "Correct maai" to me is just one aspect of maai and, to me "maai" doesn't mean "correct distance" (or somesuch). There's also, of course, "incorrect maai" (with which I am all too familiar).
If the situation is that I'm empty handed and my partner has a jo, my sense of maai will differ from that of my partner's. Likewise, my sense of maai in that situation will differ from that if my partner were wielding a shorter weapon like a tanto. And so on.
Personally, I don't think we throw away the sense of maai ever during a technique. It's just like the sense of posture, connection, and so forth that occurs during a technique; it's something that's always there, although perhaps not always there in a perfect sense...