This line of conversation was discussing it as though it was an actual game. Maybe I misunderstood the point you were trying to make in regards to "ra", and, "ist", in which case my b. To my knowledge there's no rule stopping one from laying letters down however they want in one line so long as it forms a word at the end of them doing so. One could put down "t", then "s", then, "i", or alternate "r", then "t", etc. as they're laying down their word.

Not sure what in my comment made you think I wasn't discussing rules and actual gameplay but if you could elaborate on that for my own future reference, I'd appreciate it.