I see a lot of new listings in the MLS that maybe go in on Friday and say something like "Please submit all offers by 5pm on Monday". This was a great strategy maybe back in November. However, now that more and more houses are coming on the market, that might not be the best idea.
First of all, most buyers are under time constraints. They are looking at a house today because they most likely NEED to buy a house today. If they see it today and submit a GOOD offer today, you might want to negotiate with them or accept their offer.
Some buyers don't want to get into a bidding war. I've had buyers ask me to schedule showings and when I tell them the seller isn't reviewing offers for 3 days, 5 days, sometimes a week, they tell me not to even schedule.
Buyers will have time to retract their offer. I've been on both the buying and selling end of the buyer retracting their offer before the deadline. In my buyer's case it was because something better came on the market before the seller made a decision. In my sellers case we had 9 offers and before the deadline 3 of them retracted. Probably for the same reason.
A good strategy might be to just ask all buyers to submit their highest and best offer from the get-go and for the seller to accept a good offer swiftly so they don't lose a good buyer.
As a top selling agent I have managed many multiple offer situations. I've also had my buyers offers accepted in multiple offer situations. I'm a tough negotiator and as a full time agent, I've navigated a lot of contracts and taken the time to build relationships with other agents. That makes a big difference in a Seller's Market.