Some studies have more than one part. You must sign up for all parts of the study at once, and the each part may need to be scheduled to take place a certain number of days apart from the previous part. These studies will be clearly marked, and the system will ensure you are only able to sign up for timeslots within the appropriate amount of time between each part.
In the case of multipart online studies, the time separation between parts is based on when you complete the previous part. When you are marked in the system as having completed one part of the study, you will receive an email with a link to the next part of the study, and that will also include information about when that next part will be available for participation. In addition, if the next part became available in the last 24 hours, and is still available, you will receive a reminder email about it at that time. You can also access the URL for the study in My Schedule.