1st shot is out of bounds. The player hits a provisional, it is also out of bounds, what happens after that?
If both of the first two shots were out of bounds, the player plays his fifth shot from the tee.
There’s no limit - it’s like when Sergio Garcia hit five consecutive shots into the water at this year’s Masters.
You go back and re-tee, playing your fifth stroke.
Come to think of it, that’s what they should call it, because when you’re doing it, you feel like you’re having a stroke! </RW> 
I cannot even THINK about golf without having Robin Williams monologue through my head.
Thinking it won’t is like a wee little flag over there to give you some hope. I feel for my coworkers/teammates at our charity golf tournament next month.
One of the many golf rules I think are stupid for the average recreational golfer in a non-tournament setting. Hit it OB, sure, reload on the tee. Lose that one as well - just go out there and drop one.
JMO.
Actually, it’s long been my opinion that OB should be treated like a lateral water hazard. Drop at the point the ball crossed the margin of the OB, take a one-stroke penalty. My golfing buddies played that way when I lived in Ohio, and it saved considerable time when playing courses with lots of OB along the margins of the course.
A lot of courses actually adopt a form of this policy as a local rule by treating what would normally be out of bounds on the perimeter of a course as a water hazard. Always check the scorecard for local rules when playing.
The USGA and Royal & Ancient have adopted proposed local rules, not for use by the pros or similar tournaments, that do pretty much what DSYoungEsq and denquixote mentioned. https://www.golfdigest.com/story/usga-and-randa-officials-reveal-final-draft-of-modernized-rules-of-golf-to-debut-in-2019 From it:
When I play and I hit OB, I hit a provisional, look for the OB unless it’s futile, and if I do end up lying 5, I’ll drop somewhere where I can hit an approach shot. But then I don’t play tourneys or for money—I’m not that good—and I generally pick up if I’m going to be 5 over. I’ve picked up a lot in the past…
I once caddied for my wife in a Ladies Tournament. It was an endless day of provisionals, walking back to the tee after searching for the full five minutes, arguing about rules*, etc. The round lasted six and a half hours. Not fun.
*Not me. I managed to keep my mouth shut.
Supposing you hit 3 or 4 balls OB in a tournament do you get 5 minutes to look for each ball without limit on the number of balls or does an official discreetly approach the player and suggest he might have injured himself sufficiently to seek medical attention on that last shot?