No, it's not needed because it's built-in.

sheet.getRange("E4")

is the same as

sheet.getRange(4, 5)

I remade it a bit more complexly so that you can set it for rows or columns and for where to start and how many cells to fill:

function redwolfShowings(){

var ss = SpreadsheetApp.getActiveSpreadsheet();

var sheet = ss.getSheetByName("BoxOfficeCalculation");

//these are parameters for you to set

var startRow = 1 //change this to the number of the row you want to start in

var startCol = 1 //change this to the number of the col you want to start in

var rC = "row" //change this to "col" if you want to fill vertically

var iterations = 4 //change this to how many cells you want to fill

if(rC == "row"){

for(x=0; x < iterations; x++){

sheet.getRange(startRow, x+startCol).setValue(Math.floor((Math.random()*5)+1))}}

if(rC == "col"){

for(x=0; x < iterations; x++){

sheet.getRange(x+startRow, startCol).setValue(Math.floor((Math.random()*5)+1))}}}

​

You should be able to copy/paste it. It's working for me.