Thanks, that's really too bad, cuz I purposefully booked this flight thinking I'll be able to see the lounge. How long was the actual connection time bw off board and boarding time??
I recently flew SQ11 LAX-NRT-SIN. Scheduled NRT arrival is 17:50 and scheduled departure is 19:00. We arrived approx 30 minutes early, and there was no transit security coming from the US. I walked quickly to the NH lounge at Satellite No. 5 (near gate 52), and I was taking a shower by 17:40 (no wait for the shower). For me, a shower to refresh between long flights is more important than food and drink in the lounge.
They had a sign at the gate when we arrived announcing boarding at 18:30. They must have started earlier, though, because the gate area was mostly empty when I returned just before 18:30.
On SQ11, you will likely have time for a lounge visit, even without an early arrival. On SQ12, the time spent on transit security will leave you little time for a lounge visit unless you get lucky with an early arrival.