How often should I use Vitamin C serum to achieve optimal results for my skin? Is there a recommended frequency that balances efficacy without overwhelming my complexion? Considering the various formulations available, from serums with high concentrations of ascorbic acid to gentler variants designed for sensitive skin, how can one discern the ideal routine? Should I integrate it into my morning regimen, given its protective qualities against environmental stressors, or is a nightly application more beneficial for rejuvenation? Furthermore, how does skin type influence application frequency? For example, do those with oily skin require a different approach than individuals with dry or combination skin? As I contemplate the timing and dosage, could my existing skincare products interact negatively with Vitamin C? In essence, what is the quintessential strategy for harnessing the unparalleled advantages of Vitamin C serum without compromising the integrity of my skin? How do I navigate this complex landscape?