Speak for yourself buddy - everyone is different and has different genetics.
I have always had big legs for the rest of my body. My uppder body has always been a bit small in proportiion.
If I train legs with the same intensity that I train my chest and arms, my legs are TOO big to get a good, overall, proportional look. So I balance it out.
So stop worrying abouyt what other guys do or dont do, and do what works for you.
I have learned this as well, I was doing alot of ab work, and develpoing a hard muscular mid-section, but my waist was getting BIGGER, too big for what I want actually, so I backed off.
So, for me, I HAVE to work chest, shoulders and arms more. And have to do relatively less on legs in order for things to balance.
And I stopped doing targeted ab work althogether. I MUCH prefer that "V" look that Arnold, and Frank Zane, had as opposed to the "tree trunk" look that many laters BBer's have.
To each his own.