In reference to your thoughts about the length of meditation, for me, it seems to take about 15-20 minutes to really settle myself, and then, because being settled is so pleasant, I just remain there another 10 minutes or so. I usually meditate from 20 to 35 minutes, but I don't set a timer. (I used to before I was retired and I had a stricter schedule. Having a timer set meant I could relax and not think about being late.) Anyway, these days, if I "come up out of it" after 20 minutes, I just go about my day. Once in a while, I come out of it in less than 20 minutes, and then I also call myself finished.
One of several things that her statement reminds me of is the use of a timer. We use a simple kitchen timer that dings after the number of minutes set. As mentioned, the use of an audible timer may improve one's ability to stay focused on not getting embroiled on thoughts. Knowing that it is working, the meditator can stay aware of self and the world, watching the breath and the parade of thoughts.
At our age, the volume of the signal matters. My wife can hear better than I. On trips, we sometimes use my watch which has a sound signal but I can't hear it. I am the same old antsy person as ever and I am usually eager to have accomplished the day, and all its parts. Logical or not, that means that usually between once and three times in a 12 minute session, I want to know how much time has gone by and how much is left. I glance at the timer to read the dial then.
I am working on merely accepting the time passing without anticipation or agitation. Several authors have implied a sort of two-step process, where one uses one-point focus on the breath or a visual target or both and then moves to being more aware of the bubbling thoughts from the unconscious into the conscious. I find that awareness of the thoughts is happening more but I still stay on one-point focus most of the time.
