one whose lessons are well worth revisiting as many times as possible 
(ROOT (NP (NP (CD one)) (SBAR (WHNP (WP$ whose) (NNS lessons)) (S (VP (VBP are) (ADJP (RB well) (JJ worth) (S (VP (VBG revisiting) (NP (NP (ADVP (IN as) (JJ many)) (NNS times)) (PP (IN as) (ADJP (JJ possible))))))))))))
(ROOT (NP (NP (CD )) (SBAR (WHNP (WP$ ) (NNS )) (S (VP (VBP ) (ADJP (RB ) (JJ ) (S (VP (VBG ) (NP (NP (ADVP (IN ) (JJ )) (NNS )) (PP (IN ) (ADJP (JJ ))))))))))))