Fighting against those Medusas and knights wasn't so hard to me. Most of the time I just turned Alucard into mist and escaped those areas.
It was the other way around when I tried to punch those cogs on the walls. I'm not sure how much time it took to succesfully pull this of. Most of the time I got "stoned" and then pushed right into the sharp embraces of those bloody knights.
It was probably the most frustratong moment in the whole SOTN for me.
The downside to the mist at that point was if you already had the Poison Mist option and did not turn the relic off...then hit the gears. Misting is always a good escape, but not if you have to do something to get something, therefore you don't intend on escaping.
And each gear took between 1 and 20 hits to get the click. The gears were spread out in 2 different areas with the same hellacious barrage. You are right, at some point most are skilled enough to work through it, but the gears, or that ONE cheap hit you end up taking can just ruin a day....