Conversation so far:
What happened in 1967?
The strain on the group was apparent when they performed indifferently at the first Monterey International Pop Festival in June 1967.
What was the issue?
The band was badly under-rehearsed .

Question: Did they start to practice more together after that?
Self-contained rewrite: Did  The Mamas & the Papas start to practice more together after been badly under-rehearsed?