I hold a MET Daily ticket, that I validated on the metro the first time
Do I need to continue to validate it every time I take a bus/metro?
I think you need to validate only once (so you get the date and time: it is valid 24h).
Il biglietto deve essere convalidato e conservato per tutta la durata ed esibito al personale di verifica in caso di controllo.
source: Biglietto 24 ore MetDaily, and I would translate it as:
The ticket must be validated and kept for the entire validity period, and be shown to crew in case of a ticket check.
Not the best way to write it, but I think I get the meaning of such "bureaucratic speech".
No, the ticket is validated only by first marking. It prints the starting moment (and place sometimes) and sets since when, and where, it is valid from.
The end of the period is marked by the type of the ticket. A daily ticket is valid for 24 hours since validation.
Any other attempt to validate it again will render it invalid instantly. Two timestamps are understood as cheating.
You may be asked to show the ticket to the staff/driver.
The only case you might need to re-validate is: There is no other way to get in the metro/tram/bus than stuff the ticket in the tourniket.