Using any NiTi rotary systems with one length philosophy you have to create glide path up to #20 before rotary. It decrease breakage of files. Sounds logically. But in practice this stage can take you 15-20 minutes for molar and also increase chance to make an apical ledge which will be difficult to bypass. Why crown down approach is forgotten? The sequence of instruments I use is PreRace 30/.06, Profile 25/.06 for coronal and middle third, only then I try to get an apical patency. Apical part is prepared by profile #35 or 40.