PLEASE HELP, THIS IS A QUESTION I HAVE BEEN WONDERING FOR SOOOOO LONG!?

So to start, (about weightlifting and how often you have to rest...) I always wondered, is it the more you work out, you get used to it and the less you have to rest? Here's my reasoning so i don't look like a fool- olympic weightlifters, they lift weights on the same areas EVERY SINGLE DAY- how? My coaches and some personal trainers that work with us (football) always say you need a days rest inbetween workouts -another example- BRUCE LEE- he worked out hours upon hours every single day and his power was godly. you always hear how like- if you over train (or train everyday) you'll lose muscle and become weak, and all sorts of bad things... so my question is how come the powerful people ever train every single day with nary a rest? sorry, BUT PLEASE ANSWER! and if you do THANKS A MILLION.