Not really. I once happened to turn a 3-day trip into a 4-day trip without additional expenses beside meals and accomodation, for a longterm client.
The rationale was that, having he already set up the budget for me for that occasion, there wasn't more gold to dig, so to speak, so I was just giving him some more without taking away from the rate (I had nothing scheduled for the 4th day anyway); in order to improve relationship with him.
Now, if somebody's good enough that he gets 10 bookings from the same guy, I'm very persuaded that he wouldn't need at all to give freebies.
You wouldn't buy 10 mediocre experiences to get a free one, isn't it?
On the other hand, you wouldn't back off from 10 great experiences just because you won't get the 11th one for free.