Same story every year, Indian team is cash cow for BCCI and other boards so their schedule is heavily packed no matter what. I think we're are going to see rotation policy soon for all 3 format. Majority of premiere player might get fair amount of rest during SL/Zim and Asia cup if it happens.
Ideally India should not be playing against Zimbabwe, as the latter doesn't even have a stable team now. But since the tour is finalized, I would like the BCCI to send a young team led by Shreyas Iyer. The top players (Kohli, Rohit, Bumrah.etc) should be limited to matches against Big 3 plus New Zealand. For the remaining tours, they can have a rotational policy for the top players and younger players can fill some of the slots.