Apps Script Exceeded MAXIMUM_RUNNING_TIME Workaround

Question

First of all, I am continuing an old thread at this link that I am unable to comment on due to being a newbie.

I have a situation that an answer in that thread given by user Br. Sayan would really improve my Spreadsheet Google App Script. I am making calls to Google Url Shortener API, which puts quotas at 1 call per user per second. I have slowed my script down enough to accommodate this quota, but I then I run over the MAX_RUNNING_TIME for App Scripts execution due to the extended number of calls I need to make, so I need to break the loop when the execution time is exceeded and pick up where I left off.

Here is the code of his answer:

function runMe() {
  var startTime= (new Date()).getTime();

  //do some work here

  var scriptProperties = PropertiesService.getScriptProperties();
  var startRow= scriptProperties.getProperty('start_row');
  for(var ii = startRow; ii <= size; ii++) {
    var currTime = (new Date()).getTime();
    if(currTime - startTime >= MAX_RUNNING_TIME) {
      scriptProperties.setProperty("start_row", ii);
      ScriptApp.newTrigger("runMe")
               .timeBased()
               .at(new Date(currTime+REASONABLE_TIME_TO_WAIT))
               .create();
      break;
    } else {
      doSomeWork();
    }
  }

  //do some more work here

 }

My Questions:

Is MAX_RUNNING_TIME a global variable with a value set by Apps Script that I can leave that reference as-is, or must I replace it with a value equalling the 6 minutes listed as the quota for run time on the Google API Console?

How can I place the bulk of my function within this script so that a loop that runs inside my function (say var i = 0; i < data.length; i++) will be synchronized with the loop in the portion given in the above code?

Clarification: when i is incremented up by 1, I need ii to increment by 1. Does this happen automatically? Do I need one loop nested inside the other? Does the bulk of my function go in the first '//do some work here' or the second '//do some work here' or possibly even doSomeWork()?

@tehhowch agreed! However, HOW I need to adapt my code depends on where I need to put it in the above snippet.

Here is what I have so far:

'function short() {
  var = startTime = (new Date()).getTime();
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  var run = 0;
  var finc = 50;
  var istart = run * finc;
  var iLen = (run + 1) * finc;
  var startRow = 2 + istart;
  var endRow = startRow + finc;
  var data = sheet.getSheetValues(startRow,2,endRow,1);
  var shortUrl = new Array();
  for (var i=istart; i < iLen; i++) {
       Utilities.sleep(1100);
       var url = UrlShortener.Url.insert({longUrl: data[i][0]});
       shortUrl.push([url.id]);
       Logger.log([url.id]);
  }
  var t = ss.setActiveSheet(ss.getSheets()[0]);
  t.getRange(startRow,4,finc,data[0].length).clearContent();
  t.getRange(startRow,4,finc,data[0].length).setValues(shortUrl);'

So if I update the code after each subsequent run to manually increase the variable 'run' by 1, and manually run the code again, this works.

I have also tried break it down into multiple functions by updating the i= and i < parts for each subsequent function, which also works, but requires much more manual work.

I have also tried, unsuccessfully, to use a prompt with a button press that continues the function, which would be better than the other attempts, but would still require a button press to resume the code after each run.

I want to automate the function as much as possible.