Friday morning is a mixed trade and public day, the afternoon is all public and that is when some exhibitors pack up and go, as previously explained, it is all to do with hotel costs, transport including hire vehicles and keeping staff working over the weekend etc. If you come on a public day definitely do the halls first.
I put the question of a two day ticket to those that know and was told that the take-up, when it was tried before, was insufficient to cover the additional printing costs, have to admit, I hadn't thought of producing the previous days ticket for a discount!
The suggestion was, as you may expect from the commercial department, why not buy a Gold Pass and have admission on all three days?