Can I request work documents from people in other companies
(Concurrent of course), is this legal or just it is dumb idea ?
You can request anything. But it isn't common for competitors to help each other get better.
And before you go sharing your own company's information with your competition, you had better make sure you have management's written approval. In my company, you'd be fired on the spot if you did that without prior approval. And I would never hire someone who shared his company secrets without approval.
Being known as someone who shares his company's work products can be a career-limiting move.
That said, some companies share industry knowledge with each other - in seminars, in industry forums, etc.
Ask around your company first. Get permission first. Then, and only then, proceed carefully.