In reply to An Triubhas: Depending on the sure footedness of your party you can decend the east face just below adam and eve and pick up a faint path that leads you back to the NE ridge, I've always found this way to be the quickest means of getting off mount ogwen. If you still have plenty in the tank though, carry on through the south col and do bristley ridge and turn right to take in the cantilever stone & the rocky peak of glyder fach and come down via the devils kitchen, nice day of scrambling and mountain walking that is. In direct answer though HT is pretty straight forward and when it joins the bottom half of the NE ridge you can go directly down to the the milestone car park or turn right on a path that takes you to little tryfan and the camp site.
I was a lot leaner and fitter a couple of years back and we did the adam and eve to the chippy in Bethesda in one hour dead! Summer though, don't be trying to beat that in present conditions! Enjoy, I always enjoy a day on Tryfan