The logic behind it is for recon purposes. IME, the CSRs are slammed Monday from all the apps/problems over the weekend and sometimes that bleeds over in to Tuesday morning. If you app Tuesday afternoon/Wednesday, you have a better chance of getting someone live on the phone Weds/Thurs if you need them. Moreover, Mondays and Fridays are the most likely days for supervisors/csrs to "take off" due to illness/vacation/whatever. So Tuesday/Wednesday/Thursday (Wednesday in particular) would have a higher likelihood of a fully staffed call center.

Basically, it boils down to not having to wait for the recon if you need it. That's it, nothing too special.

Cheers,

-SM
(Note: NFCU is different, they recon all weekend, but their recon is them calling you if you aren't immediately approved.)