You benefit from every meditation class or individual mediation you do. The benefit is cumulative, so the more you meditate, the greater the benefit.
Aim for meditating daily.
You could attend one meditation per day, or you could attend multiple meditations per day, to get yourself back on track. Think about a stressful day at work, and find classes that fit between your meetings, to bring yourself back into a calm and centered space.
You can also attend classes just on nights or weekends. Every class is unique and beneficial to your body, your mind, and your soul.