Our rule of thumb is to hold pressure on a tender spot for 20-30 seconds. Ideally, in this amount of time, you would feel a change in the tissue, such as a reduction in discomfort or tension. You can give it up to a minute to see if there is a change. If no change is felt, give it a break and come back to that spot later.
Our rule of thumb is to roll until you feel a change in the area you're focusing on. In most cases, this happens between 45 seconds to 1 minute. If after 1 minute there has been no change felt, give it a break and come back to that spot later.