It depends on your confidence level. If one has a negative self-image it is very helpful to use it regularly. It is very difficult for me to say you should do this a certain amount of time, because everybody is so different, but if you have a tendency to become negative about your practice or yourself, then reminding yourself about the Ten Paramis with this meditation is very, very helpful. It will keep our practice directed towards the Paramis, we know how to judge our practice, less on concentration and mindfulness and more on our Parami development.
As far as keeping our practice going perhaps it is good to do it once a week, because then you realize that the Paramis are your direction in life. One old student got very creative and used the Ten Paramis as a once a week activity, that is the first week they focused on Generosity, trying to increase the power of Generosity in their practice, and this went over 10 weeks. Very good practice. In that way actually they were trying to increase their understanding of that Parami daily. One other suggestion, in order to reflect on the Ten Paramis, it is good to memorize them.