Can be used to help with determining if two ranges intersect and the intersection range.

SpeaSheetRangeMaskIntersect.gs

const isEnabled = true
const numberOfShiftGroups = 2

function onEdit(event) {
  console.log(`Event range: ${event.range.getA1Notation()}`)
  if (!isEnabled && event.range.getSheet().getSheetName() !== "Shifts") {
    return
  }
  const speadSheet = SpreadsheetApp.getActiveSpreadsheet()
  const shiftsSheet = speadSheet.getSheetByName("Shifts")
  const highlightingRange = shiftsSheet.getRange("A:B")
  if (rangesIntersect(highlightingRange, event.range)) {
    const overlapRange = {
      row: event.range.getRow(),
      col: event.range.getColumn(),
      width: event.range.getLastRow() - event.range.getRow() + 1,
      height: (event.range.getLastColumn() >= numberOfShiftGroups
        ? numberOfShiftGroups
        : event.range.getLastColumn()) - (event.range.getColumn() - 1),
    }

    const highlightingSheet = speadSheet.getSheetByName("Shifts Highlighting")
    const cellsFormatting = highlightingSheet.getRange(overlapRange.row, overlapRange.col, overlapRange.width, overlapRange.height,
    )
    console.info(`Formatting range: ${cellsFormatting.getA1Notation()}`)
    const cellsToFormat = shiftsSheet.getRange(overlapRange.row, overlapRange.col, overlapRange.width, overlapRange.height)
    cellsFormatting.copyFormatToRange(shiftsSheet.getSheetId(), overlapRange.col, overlapRange.row, overlapRange.height, overlapRange.width)

    console.info(`Done for range: ${cellsToFormat.getA1Notation()}`)
  }
}

/**
 * Recycled from https://stackoverflow.com/a/67916559
 */
function rangesIntersect(r1, r2) {
  if (r1.getSheet().getIndex() !== r2.getSheet().getIndex()) return false
  if (r1.getLastRow() < r2.getRow()) return false
  if (r2.getLastRow() < r1.getRow()) return false
  if (r1.getLastColumn() < r2.getColumn()) return false
  if (r2.getLastColumn() < r1.getColumn()) return false
  return true
}