Since I've recently decided to primarily use Big 3 Free nail polishes, with the "Big 3" being toluene, formaldehyde, and DBP (dibutyl phthalate), I've been paying more attention to them and how other people are using them as well. I thought I'd pass on the results of some of my own experience and some research I've done on the topic in light of something I've observed.
I've noticed other ladies doing something which I've found does not consistently work: mixing Big 3 Free products with "regular" products, or those which do contain any of the Big 3 (in my experience, specifically toluene and formaldehyde). By mixing products I mean combining a base coat and color, or color and top coat, that are not of the same composition. What's happened to me with that is (i) using a toluene containing top coat over B3F color resulted in the nail polish coming off in large chips within hours, and (ii) using a formaldehyde containing base coat under a B3F color resulting in severe staining of the nails. Mixing products may work for a given color, but odd results may also happen - it simply is not predictable, and is thus not recommended.
I'm not suggesting that one should necessarily stick to using the same brand for base, color, and top coat, but that one should be aware that B3F products are not intended to be combined with toluene, formaldehyde, or DBP, and strange outcomes can occur when they're mixed. I do know that several of the B3F companies, notably Zoya, Nubar, and Carolyn New York, strongly recommend the use of their own base and top coats with their color.
To be honest, I've been mixing brands myself, using Nubar Nu Nails Nail Strengthener as a base and Nubar Diamont Seal & Shine Quick Dry as a top coat with Nubar, CNY, Orly, and Zoya colored nail polishes and have had fine results. I just wanted to point out the companies' recommendations, as it's likely a "your mileage may vary" issue.
I just wanted to get that little product rant out there, Dear Reader. Now that it's out I can say until next time, love and nail polish to you!