Is "at a time" correct?

Question

I would like to find a way to express the meaning of "at some time". For example: > I think everyone has his study or working rhythm **at a time**. This rhythm varies for different person, and may be different **at a different time** for the same person. Especially it can > change over time as he becomes more experienced. So pacing them at a pre-fixed pace may not work well. **At a time** sounds awkward to me. What do you think?

Answer 1

You are correct. I believe the awkwardness stems from a slight error in phrasing. A rhythm is a pattern over time and therefore cannot be said to take place *at a time.* What you are trying to say is that in each person's mental/emotional rhythm, there are optimal times for study, work, and so on. These times occur at different frequencies for each person and an individual's optimal study or work habits may change over time as their frequency changes. Furthermore, in a monochronous society it is inevitable that there will be discontentment and loss of efficiency and fervor if people are forced to adhere to an arbitrary schedule.

Let me know if I lost your point or if this is wholly disappointing.