Are their any drawbacks to lifting weights every other day?

I like to lift free weights(heavy) every other day...bench press, bicep curl, squat, and forearms. I have been told that you should only train a muscle group once a week! However i do this every other day and am definately seeing progress. I guess my question is is it ok to work out every other day as long as theres always that 48 rest period between sessions? Im asking because id hate to think that im out there busting my for nothing...or to be doing more damage than good?