I generally avoid those independent shore excursions. The local tour operators just can't be relied upon to give you access to "authentic" Third-World landfills. I mean, if you want to get up really close to the long-tailed pygmy rice rats and their aerosolized feces, it's best to go with the ship‑sponsored excursions every time!
Regards,
But apparently the non-sponsored guides at least got them back in time for departure. I always love watching the idiots run for the ship. It isn't like they make the departure time a secret.