Price is the term buyers expect to see change, but a counter-offer can adjust the possession date, the list of included chattels, the conditions attached, or the deposit amount, and any single change restarts the clock on the other side's response.
Every counter-offer needs its own acceptance deadline, because without one either party can walk away or entertain another offer while it sits unanswered. That is a common surprise for first-time sellers who assume a counter-offer holds the buyer in place the way an accepted offer does.
Joel Dyck drafts and negotiates counter-offers for Saskatoon sellers so no term gets left ambiguous. Get your hand-reviewed valuation from Joel Dyck.