In these situations if in fact the buyer is going to default you must notify the escrow to start the cure period. It doesn’t commence automatically.
Compare it to say...a property you have rented out. If the tenant doesn't pay his rent in California you must give a three day notice, then file and serve the unlawful detainer. i.e. You must take affirmative action to enforce your rights, they don't kick in absent your action.
I’m in a two year payment plan with a buyer who gave a substantial down payment towards a high five figure purchase price. Given the high down payment buyer has no incentive to default. Many times he’s submitted the credit card payment form only to have escrow.com be very slow about processing it. Also, escrow.com accepts max of $5k of credit card payments per six month period beyond that buyer must bank wire.