The most time savings I’ve ever had has been 5 min.
I think there may be a few occasions where I've "saved" more than 5 minutes, but the thing is, it's not a consistent, reliable enough savings to actually change my behavior. I still arrive at the airport at the same time, so any time "savings" is just an illusion. At best you're trading 5 minutes of time staring at your phone while you stand in line for five minutes of time staring at your phone in the lounge or at the gate. And while I'd rather be sitting than standing for those five minutes, I'm not going to pay any actual money for that.