There used to be a governor that didn't allow trades to go through immediately between those hours and that governor, for whatever reason, was moved so that now trading is slowed in the middle of the afternoon rather than during the reset hours which is when it is needed. This governor which was very apparent in the old HSX basically meant that trades took 20-30 seconds to go through so that one couldn't immediately profit from reversing stocks at reset. I still see this slowness of trading during afternoons on the East Coast for some reason where I make a trade and it takes time to go through and there's no reason why those trading during normal business hours should have to wait for trades to go through to free up cash. (This governor mainly affected smaller ports because it meant that cash from selling/covering wasn't freed up immediately.)
I hope whomever from HSX reads this knows what I'm talking about.