Possession date matters most often in practice. A seller who needs an extra 30 to 60 days to arrange their own move can counter on timing alone, which costs the buyer nothing but solves a real logistical problem for the seller.
Conditions are the other lever. A seller facing two similar offers might counter to shorten a financing or inspection condition on the stronger one, since a shorter condition period gets the seller to a firm deal faster with less risk of the buyer walking.
Joel Dyck helps Saskatoon sellers see which lever actually solves their problem before a price gets touched. Get your hand-reviewed valuation from Joel Dyck.