Accordng to the dictionary, the expression with "over" can be used to "say how many times the same thing happens" or "say by how much an amount is multiplied".
These are the given examples:
1 – He sings each song twice (over).
2 – The pattern is repeated many times (over).
If I haven't known this example of "over", I would have used these sentences, for example, without "over".
Best Answer
"Once-over" is usually applied to an examination of some sort. Examples: "I gave my question a once-over for errors before I posted it." Or, "My son cleaned his room but I gave it a once-over and he didn't do a very good job."
"Twice over," "three times over," etc. generally only refers to the repetition of events. Example: "The car was so dirty that I had to wash it three-times-over." The "over" also usually implies that under normal circumstances, repeating the event that many times would have been excessive.
"Twice," "three-times," etc. without the "over" can refer to events but can also refer to multiplication of nouns. An event example can be as simple as, "I washed the car twice a month." A multiplication of nouns example would be, "I had two oranges and then somebody gave me four and now I have three times as many."