There are several synonyms for the phrase "concentration time" that can be used to describe the amount of time someone is able to focus on a task without distraction. One of the most commonly used terms is "attention span", which refers to the length of time someone is able to pay attention to something without getting bored or distracted. Other synonyms might include "focus duration", "productivity time", or "work intensity". Regardless of which term is used, it is important to recognize that each person's concentration time can vary depending on a variety of factors, including their level of interest in the task, their level of fatigue, and external distractions.