I'm not sure where you got that idea. you raise the FC level back up to normal levels after only 24 hours. However, you don't want to shock for 2 weeks because shocking before everything has settled down can cause the stains to reappear.
It's not that you don't use chlorine for 2 weeks, but rather that you don't shock for 2 weeks (see this post for the ascorbic acid treatment instructions). I believe the main reason is to prevent the pH from rising since adding hypochlorite sources of chlorine raises the pH upon addition. As noted in the post, you want to maintain a lower pH and have it slowly rise up over time. Specifically, the post says the following:
Do not shock for at least 2 weeks! Make sure you keep your ph low for (7.2) for a week or two
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