CHOP simply states “It is not recommended that bids close on a Friday or a Monday, nor immediately following or preceding a statutory holiday”. 
 
On Fridays, everyone wants to get away for the weekend, and there may be routine tasks such as submitting time sheets before leaving for the day that may distract anyone involved from devoting their full attention to preparing the bid.
 
Mondays’ a probably worse than Fridays. Statistically, you shouldn’t buy a car made on a Monday. They have more deficiencies and quality problems than cars built on any other day. The workers may be upset because their team lost on the weekend. They may be hung-over from celebrating a victory. They may be tired from too much partying, or they may be out of sorts because they have a full work week ahead of them. Bid preparation on a Monday is subject to the same influences.
 
It is worth looking into the potential for other bids to be closing on the same day or in the same week as you are considering closing your bid because multiple bids closing on the same week can result in escalated bid prices or receipt of fewer bids at closing, especially if another project is perceived as higher profile or potentially more profitable. When multiple bid closings occur too close together, general contractors, subtrades and suppliers become overwhelmed which can result in less competitive bid pricing and may also increase the risk of errors or omissions in bid prices.