Dear Miss Snark:
What is your feeling on requests for a writer to revise a novel multiple times before a contract? Do you advise your clients to do this? Is the editor taking that particular writer for a ride? How often do you see these revision efforts pay off at the house where the revisions were requested?
Pay to play babeeee.
I don't like to do extensive revisions without a concrete expression of interest and some money i.e. a contract.
If they like it but not enough that means "no" and it's really hard to get to yes from that. Better to shop elsewhere or start again.
When I call an editor, the question is "do you want to buy this" not "what will it take for you to buy it". yes/no/show me the cash.
On the other hand I've had very very intense conversations with editors about they'll want changed if they offer and I make sure the client is ok with that before we sign up.
And this is always the client's call. If they want to revise without a contract I'll let them do it but I hardly ever advise them it's a good choice.
This is a classic example of "your mileage may vary" so don't write this down on that Stone Tablet of Snarkly Commandments.