If OMR sheets remain folded for many hours, marks near the crease area might not be scanned properly. Folding or rolling of OMR sheets should be avoided, so to ensure accurate evaluation of the OMR sheets.
In some cases, crease lines are indicated on the OMR sheet. If you need to fold the sheets, fold them from the crease line.
In many competitive exam OMR sheet is attached with a booklet. It is important to pay attention while detaching sheet, so you tear from the perforated line only.
Printers used for the printing of OMR sheet must be of good quality so that perforation line indicated on sheet is clearly visible and sheet can be torn easily, thus decreasing the chances of damage caused due to folding of OMR sheet.