Mix things up a bit although heavy squats are best for growth, and strength try to incorporate other forms of leg exercises maybe different rep schemes or try lunges out for a bit add in some front squats. A good amount of variation is key to leg development, i wor out my legs twice a week once i do heavy squats and use a lot of the wellknown movements i guess then a second day i do some odd exercises starting usually with cleans and getting into walking lunges, physioball bridges, jump squats, and other either pylometric or strength exercises.
But one thing to think about is the key to gaining strength is progressive overload that puts stress on your muscles, your muscles adapt to stress there not used to by adapting to give them ability to manage that stress i.e building more muscle. So work to or close to failure and thats when i see the best results, some people have good results with low weight high reps its all about overload though in my opinion and mosts.