Do you do them standing on a bench or platform ? The stretch very important. But as said your frontal overshadows the hams but all the way some big legs.
ur right i should go back to platform version.been doing regular standing for a long time,,,i do seated and lying leg curls and i do good balance of hi rep and low rep ,,i like 10/12 tho and with most leg movements i use stack on them,,i have very strong legs squatter,leg pres,lunges ,i'm no platz disciple tho i still have good balance upper to lower ..but good legs is never a bad thing,,,