i have a hair mask i apply maybe once a week. well more like every 2 weeks because i usually forget. no particular brand - my salon gives me huge samples whenever i go and they usually last until the next time i go in. it's been mostly kérastase and l'oréal professional and they've worked fine on my hair but mostly i swear by my kérastase conditioner. it's called ciment anti-usure and i apply it to the bottom half of my hair every time i wash it (i have oily hair so i keep it away from my roots) and it's really made my hair stronger and shinier and more manageable. it's expensive but it lasts for ages.