The polymathic Ginger Stampley talks about randomizers and when to fudge their use over on the 20' by 20' room.
One of the hardest things about doing a game like Amber is the very fact that it is diceless.
Amber is a game about competent characters. And game systems like Heroquest have "Masteries", where a character basically, without strong opposition, always succeed on a roll. I feel there is a time and a place for having competency handled.
On the other hand, though, true randomness says something about the Universe and can be useful in a universe where the unexpected happens. As a GM, in non Amber games I would employ dice to take things in unexpected directions--even to me. I took care in random encounters and events, so that they had value beyond time and space filler.
As an example, a party of D&D characters in a game I ran came across a wandering monster. The unlikely dice rolls dictated what was then called a "Type I demon."
I asked myself why they would come across such a thing, and turned a random encounter and retconned it into a plot device. It was an assassin, sent to harass and hurt the characters, an old enemy of theirs resurfacing after a long fallow period.
I wouldn't have thought to do it right then if I mandated every encounter. The dice proved useful in that context.