This was how my OMM felt; only we had 4 hours per week. If I'm being honest, sometimes I think even our faculty didn't understand what they were trying to teach us.
That being said, I felt like the OMM portion of the COMLEX a went OK; not too difficult. Just focus on sacrum, you need to be able to make the correct diagnosis based on a description of the motion of the sacrum. (Anterior right sacral sulcus, left STL tight, most likely left on left torsion. Etc.) and similar for vertebral dysfunctions. Once you have those down you'll be alright. The main thrust should always be the sciences.
I will say that I screwed up a case real bad on my COMLEX-2 PE because I didn't know a particular technique that I needed to do. Still passed though.