I've only experienced it once, but not seeing streets in the past or future, I just 'lost' 15 minutes. I used to work 10 minutes walk from home; we started at 9am so I left at 8.50 every morning. Apart from a watch, I have clocks dotted around the house so even if one of them had been wrong, they wouldn't all be wrong.
That morning I left at 8.50. My walk was down quiet residential side streets with only one slightly busier, but not main, road to cross. When I got into work, the clock on the back wall said 9.15 and all my colleagues were already sitting at their desks (instead of tea making, which they would have been at 9am!). I expressed surprise at the clock saying 9.15, to which one of my colleagues replied that it was 9.15.
I apologised for being late but said I'd left home at 8.50 and I had no idea where the 15 minutes had gone. I hadn't forgotten something and returned home for it and I hadn't bumped into anyone I knew en-route and stopped for a chat. As far as I was aware my walk just took the normal 10 minutes, when it actually took me 25 minutes 