I think cycling heavier weights for longer periods of time is fine if your diet is good and you are training smart. Meaning, paying attention to form to avoid injury.Plus taking rest days for recovery.
I have been doing the same weight/heavy to moderate weight workout for the past 12 weeks with great results. You do need a break after doing this for a long time, I plan on doing circuit type training for a week pretty soon to give my tendons and ligaments a break-along with the mental break you need after going all out for so long.I like Cathe's 4DS rotation she did, I forgot which month it was though. I did the whole rotation and loved it!
I think every body is different though, just listen to your body and eventually you will find a formula that works for you.I know I wouldn't get the same results just doing lighter weights all the time, I personally need to lift a little heavier to see the hardness and definition I like. But of course, cardio and eating clean factors into that as well.