You certainly don't need a battery switch on a Roadster. Mine starts fine on its six year old battery after as much as a month. I do give the battery a top up overnight on a smart charger every couple of months though particularly in the winter.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone