once that digit mod 5 is the same as your starting digit, you are done
That assumes there is at least one entry for each minute... What if the log looked like: 
2:00:00 all is well
2:01:00 all is well
2:02:00 all is well
2:03:00 all is well
2:04:00 oops, reboot
2:21:00 all is well again

[download]
I think looking at more than just that one digit is wise.

-Blake

In reply to Re: Answer: Can I regex & grep to select contiguous lines? by blakem
in thread Can I regex & grep to select contiguous lines? by dpenny

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