With all due respect, sometimes it's not feasible for people to attend a con for a whole weekend and so everything does have to be done in one day. For the most part, I'm a weekend attender and I did all three days of DSTE but a couple of years back I attended LFCC for the Saturday only and it was a very hectic day for me. I had about 16 autographs and 9 photoshoots all to do before the 6 o'clock train back up to Newcastle. But I don't have loads of money and I don't think I was being greedy.
I wanted to meet as many of my idols who were there as I possibly could cause it's impossible to know when or if Showmasters will get them back. My family is not a rich family. We're very working class and from, what I read (and may still be), the statistically poorest region in the UK. It's always an honour to be able to do cons. I don't go out drinking at night (I'm just not a drinker) and I don't smoke like a lot of my friends so I was able to save my money for a long time to do the Saturday at LFCC. Uni was stressing me out and I wanted to meet a few celebs to wind down. I could only do the one day though as my funds would only cover the trains and the con and would not stretch to a hotel.
I understand what you mean by wanting people to relax and enjoy it but sometimes, just sometimes, I MUST DO EVERYTHING IN ONE DAY (as you put it) is the only option for some people. And calling people greedy for wanting 10+ autographs/photos in one day or assuming that they're made of money for being able to do that or even suggesting that Showmasters shouldn't allow it is assumptive (again, I'm a far from rich), rude (calling anyone greedy is) and unkind (suggesting someone shouldn't be allowed to meet as many people as they want when they have the money to is unfair in the extreme). I'm not calling you these things personally, I only mean to say that your particular comments in this case can be interpreted as such.
And one guest cons are not going to be a popular idea in any universe.