Where it affects you is timing on possession day. If the buyer's condition period or financing condition is tight against the lock's expiry, your lawyer and theirs will coordinate through Information Services Corporation to make sure the mortgage is registered and funds are ready before that date passes.
A seller can help by keeping the file moving: responding to condition requests quickly, providing documents the lender asks for without delay, and confirming possession date early so there is no ambiguity for either lawyer to chase down at the last minute.
The lock is the buyer's lender's commitment, but a well-run file protects everyone's timeline. Get your hand-reviewed valuation from Joel Dyck.