回複：恩，又去讀了，看來11頁的說的是滿6年後的申請延期，第7

Yours is a wrong interpretation due to misunderstanding English language.
3-year limit here is the limit of ONE H1 extension (one I-129). For example at H1 after 3.5 year, your current I-797 is expiring and you meet AC21 106(a) 365 days pending requirement, therefore, you need an extension. If you don't meet 106(a) you can only request 2.5 years extension. If you meet it, you CANNOT request 3.5 years but can only ask for 3 years due to the 3-year limit stated in 8 CFR 214.2(h)
It is not referring to 9 years limit if I-140 not approved.