It won't be worth it for SQ25, maybe in F, but not otherwise. I can't imagine ever planning to stay in any airport for a 12+ hour layover. Back in 2019 I had a 12hr layover in CDG on the way to HKG (super-cheap J fare) and I spent a lovely (yet overcast and cold) day in Paris eating crepes and duck confit and having the entire 3rd level of the Eiffel Tower to myself because it was in a cloud.