Attempting to memorize complex information in one sitting doesn’t work well for most people. It’s much more effective to review the information several times spaced out over the course of several days.
Perhaps you can spend every day for a week memorizing something. Then, you can make it 2-3 days a week for the next two weeks. Eventually, you’ll only have to spend one day per week. There isn’t a hard and fast rule. The complexity of the information will dictate the schedule.