Upvote:0
I remember reading a sutta regarding Buddha told Bhikkus to be mindful of King's will (law of the land) .. this event was from when king Pasenthikosola (if I remember correctly) wished to move planting season in his kingdom (sooner or later, I don't remember), Buddha then instructed Bhikkus to observe rainy retreat accordingly. This is a quick answer as to monks need to be mindful of the local laws. Sorry if I can't find a reference at the moment . Maybe someone remembers it better than I do.
Upvote:1
It's not a matter of how long, since you can't know for certain anyway. If you perceive it to be abandon, then you can go ahead and use it as deem fit.