Never needed it.
I don't bring it with me anymore, vacation is vacation.
One time it was suddenly really an issue that I was away for a week and my employer sent a replacement to my client (for four days, so useful!) and I spent some time on the phone telling my replacement where everything was.
And then there was that time when a coworker called me, which he never did, so my heart skipped a few beats before going into overdrive mode.
Called him back, wrong number, didn't even know he called me