Upgrading from 3.7.3 to 3.7.15

Ok, I know, I should have done the intermittent upgrades, but I didn't. I plan to upgrade manually so that if something is amiss I can go back to 3.7.3 until I figure out what to do.

I see in another post that it might be better to do the upgrades in stages ( http://forum.bytesforall.com/showthread.php?t=21394 ) - that was 2.6 to 3.7.13, although some versions were skipped, including 3.7.3.

Do I also need to do this process going from 3.7.3 to 3.7.15 in steps, rather than going directly from 3.7.3 to 3.7.15?

Once I get it up-to-date I plan to put my header images, logo and favicon in the new image location as per Juggledad's instructions (in http://forum.bytesforall.com/showthread.php?t=8520).

I am also curious about Juggledad's new note at the top:

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As of 3.7.12 I recommend putting the header images. Logo and Favicon in an external file - using the new 'Image Locations' option - and then doing automatic upgrades (after doing a backup of course).
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it seems to contradict what is said in step 1 of the instructions, and I'm wondering why the change.

Anyway, as always, thanks for any help you can give! And now that I have a bit more confidence about updates I'll keep up with them!