One of the things that makes a huge difference in how much your choir accomplishes is what I'll call the "density" of rehearsal. By that, I mean that the ratio of hard, focused work on those things that need it (versus the time that isn't so productive).
There are lot of things that go into this, much that has to do with you and not your choir: your preparation (knowing the music, knowing what will be challenging or not), having solutions for problems at hand (rehearsal techniques/devices), having a well thought-out rehearsal plan, etc.
However, part of it is convincing your choir (building the culture) for hard, focused work.
I'll go back to Doug Lemov and John Wooden for this (and much more about both in future installments): Lemov (author of Teach Like a Champion) has a new book called Practice Perfect: 42 Rules for Getting Better at Getting Better. Lemov's rule 7 is "Differentiate Drill from Scrimmage." One of the noticeable things about the way Wooden worked his UCLA teams was to spend much more time in drill (focused on specific skills) than scrimmaging (playing a mock game). The advantage was that in drill, he could focus his players' work on skills and techniques that needed work (passing, shooting, defence, etc.), whereas in a scrimmage, only one player had the ball at any one time and less work for each player.
I introduced this idea to my choir this fall, equating scrimmage with a run through of a piece or section of a piece--valuable for both me and them to see where they were, what worked well and what didn't (and, of course, to get the experience of singing through the entire piece, which is what they'll do in the concert). However, I explained that we would accomplish most with drill, where we worked the difficult sections of a given piece of music, or focused on pitch, vowel, rhythm, vocal technique, or whatever else needed special attention. Sometimes, I simply said, "scrimmage," so they'd know they were doing a run-through, and to work towards what the performance would be (and to note what was and wasn't ready yet).
In drill on the other hand, they knew they were going to do multiple repetitions of something, perhaps only a few notes, but with great focus on whatever elements were brought to their attention.
They got the concept very quickly, which has meant a much greater rehearsal density for this choir. There are other elements in building this, but I hope you get the idea as well.
Of course, the level and age of your choir will determine how much and how long you can focus on small, but important, elements of the music, and how many repetitions are possible before you need to move to something else. We all have to figure out what the attention span is (although part of building a great choir culture is gradually lengthening and deepening your singers' abilities in this regard), how quickly to pace, how quickly to move from one activity to another. However, even with young singers, I've seen incredible concentration and focus -- and not all in "elite" situations. It's amazing how much young people can learn to do, given a wonderful conductor with the skill to teach them!