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I agree with the above posts. Every job is different.

If you find the problem and it is clear cut that that was the problem you replace the part and 2-3 cycles should do it. I would start it and check a safety; start it check another safety etc so your checking the part and looking for other issues at the same time.

On intermittent problems you sometimes never know. Do some testing and then it's "try it"

@mattmia2 Exactly

@HomerJSmith Great diagnosis method. So may you techs just start replacing parts without diagnosing

Here is the link to the video

Once I determine what the cause of the intermittent problem is, then fixing that item is good for me. I might try 3 to 5 cycles.

For example: You have an ignition transformer on an oil burner that fails to ignite the burner 3 to 5 times a week. it is probably caused by the transformer heating up and cycling off by the limit and then cycling back on in a short time. the warm windings on the transformer fail to make a spark. the burner goes off on safety. By the time anyone realizes there is no heat, the transformer cools off, so when the reset is pushed the burner lights properly with no tell tail sign of a problem.

After cycling the burner 20 times on the third call for the same problem you find the transformer fails to light the burner and it is hot to the touch. Viola! bad transformer. Replace the transformer and test the burner with one or two cycles. Problem solved. But that is because you are sure the transformer IS the problem.

That may not be the case in every intermittent problem though. If you are not 100% sure you got it right, like cleaning a flame sensor, and you are doing the lower cost repair first with the possibility that a more expensive repair may follow, then I may cycle several times. Every problem is different.