Yes you right. If any traders have some trading experience in before or if any traders learning skill is good then, he can practice trading with demo account 3-4 month.Six months is the standard time to learn demo account because so many traders get ail before six months, so I during experience demo account having great increasing and improvement of skill, then start in the real trading account already familiar with the trend market
But if you are a new then, six month is the perfect time for learning trading with demo account.
Demo account is not a real account, but its can provide you real trading experience without loses.