Here’s a good case: I travel far for my job. I wake up early and daven close to my office (near Yehupitzville, Long Island). Sometimes there may be traffic along the way, which means I’ll have to start before entering shul.
Another possibility: He davens nusach Sefard and is going to an Ashkenaz minyan, so he’s saying the additional tefillos that Ashkenaz does not say, whether in korbanos or the beginning of P’sukei D’zimra.
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