We left Oiseau Bay around 9am and then we got into Hattie Cove around 7pm. So that's 10 hours and we were stopped for at least an hour for lunch b/c we got a bit mixed up on the beach and couldn't find the actual trail again. So I'd say we spent 9 hours covering that distance for a moving average of 3.4km/hr. We put in a good effort on the trail and a decently long day. It wasn't a gruelling pace, but I don't think this section would be enjoyable at much of a faster speed. Travelling at 2/3rds of this pace (2.3km/hr moving average) would probably be an enjoyable speed for a decently in shape hiker, and then you can decide how many hours per day you want to walk. This is actually pretty close to what Pukaskwa recommends (they say 14.5 hrs to Oiseau Bay, which is 2.1km/hr). In person the rangers seem to be pretty discouraging of optimistic goals, but the Pukaskwa website actually recommends 5 hrs to Willow River, which is how long Rog took, so my suggestion is to take the hour estimates at the link below at pretty close to face value. Don't assume to be substantially faster unless you're packing light and willing to work for it. Longer hours (rather than a faster speed) are a more realistic way to cover more ground.
The "ruggedness" of the trails is a very relative thing. Pukaskwa's trails aren't treacherous in the sense that you aren't likely to slip and go over a cliff (well maybe if it's raining, but it's less sketchy than half dome). They are, however, slower walking that more manicured areas. You need to pay attention to cairns when you're on the bedrock sections and there's a lot of small up and downs. On really nice, low gradient manicured trail (such as many National Parks in the USA) one can walk about 50% faster than they do in Pukaskwa.
With all that said, people, weather and experiences vary widely so don't take my word for any of this. If you talked to this guy you'd get the opposite message:
We were going to stop at the White River, but we got talking about burgers, beers and a hotel so we pushed on to Hattie Cove. We did cover a lot of ground in this trip in a relatively short period of time, mostly because my wife (and work) would only give me the week off. I would have loved more time - especially on the river portion. There were so many awesome areas that would be great to stop and fish, suntan or run rapids. Then again, we got very lucky with the bugs. In peak bug season those activities would lose their appeal.