Many other larger value transactions of this nature do have an execute by date actually baked in. So while no contract exists without consideration, a real estate, business acquisitions etc often have a closing date associated with the agreement (which can of course be modified). I've liked this on transaction side (not a lawyer). What are difficulties with having a time frame to perform within?

Ie, safe must be funded within 2 business days of date of safe. Can always do a new safe if the first doesn't go through and you still want to do business?