Day FiveMost would argue that C6 is the "deepest" you can get in w-space. And maybe it is. If you mean what it takes to live, defend, farm and pvp there I guess you could say that it's the hardest. Or at least where the stakes are the highest. But logically, and most definitely logistically, it's not the deepest. That would be a C4/C4 - no question.
Why? Well, C4s is unique in the sense that they will never connect to k-space. Ever. And if your static is also a C4 you have a guaranteed route to empire of 2 or more systems. If you also take into account that a static in a C4 is much harder to roll than a C5/C5 for example, and the fact that C4's more often than not just link to another C4 it is much more work to find empire from a C4/C4.
Today I had some new sites spawn, like gas and ore sites. I initiated them by starting a warp to each of them. I want to keep the system clean so I don't have to re-pin a lot of gas-sites each day. Of course, knowing what each sig represent is vital to any kind of operations in a w-space system. That piece of information gathering is something you just can't skip if you expect to live long and prosper.
I had discovered that one of my scanning alts had a clone that was way outdated. He needed to get to k-space to update it, ASAP. I found a C5 that led me to a C6 that had a static low sec, so that would work. Only possible problem was the C6 was the home system (or one of?) of The Last Chancers, a well known and active w-space alliance. They might have a lot of active eyes on things and even be rolling their static in a heartbeat, so if I wanted to get back the same way I needed to be careful and quick.
Not to many ships on scan in the C6, and when I jumped out to low sec I got the explanation. They where all out doing some shenanigans because they had a nice little 15 man T3 gang hanging on their static. And I was right in the middle of them! Yikes. But as I burned away from the WH, I could re-cloak safely. I started to look for a station where I could update my clone. I wanted to get back in as soon as possible.
When I got back to the TLC's low sec system they was still on the WH, but now they had a interceptor there. I guess they wanted to have a better chance of catching me when I got back. Or the ceptor was there for some totally different reason. It was not easy to know, but since I was the only extra one in local, they probably knew I was coming. Together with a bit of bad luck and a bubble on the other side of the WH it could potentially spell pod-kill for me. New clone or not, I preferred to live, so I just waited some.
Patience is another piece of the w-space puzzle that's really important, especially if you are solo. In this case, they got bored before me, the interceptor jumped back home, and a few minutes later I followed. Back home in a new clone I logged for the night.