The article shared by @anil_am22 do mention that you can apply for a 7th year H1B extension if the approved PERM was filed 365 days or more prior to the H-1B Extension application.
To your point if your spouse will be eligible to recapture any time spent outside the US during the H1B term. She will also be eligible for 1 year extension if her PERM is pending for more than 365 days.
She should consult her employer’s immigration lawyer and discuss her options so she can extend her status beyond 6 years.