I've done extensions and did them continually for about 6 months. Meaning, I got them put on and then had them filled about once a month. For those that don't know they are different than false lashes. They are glued on individually or in small clusters. They last for about 3-4 weeks more or less.
I loved the look it gave my face. Instantly feminizing, they are lovely. But they are also hard on your natural lashes. Before I first tried them my lashes were fairly long already, but the extensions thrashed them and reduced them to very small weak hairs. The main thing I didn't like though was that you are not supposed to rub your eyes at all with them on and you need to be careful when washing and drying your face, no harsh rubbing of the lash area. Blot to dry.
Anywho, I stopped using them when a friend gave me some Latise, an eyelash serum. Now my lashes are full and lush without extensions. They are not quite as long as the extensions, but they are much easier to care for.