Several statements on a single line
ObjectScript does allow more than one statement on the same line, and in fact if you use legacy flow control statements (which you shouldn't, really) you even have to put more than one statement on a same line.
However, this can lead to quite confusing code; recall that statements have no delimiters bewteen them other than spacing. Consider:
// If c is true, write variable "x" then quit if c w x q
// Create a variable named x, then invoke a method on it set x = ##class(some.Class).%New() do x.someMethod()
For readability reasons, it is therefore strongly recommended to always put statements on different lines.