I'm hoping you must have done this trip safely, but I wanna share my recent experience from LHE to KHI with my wife.
It all started in Lahore when I bought my vehicle here a month back. I'm originally from Karachi so had to drive back to my hometown. I was pretty much a newbie when it comes to driving on motorways before this trip, the longest trip I ever had was from LHE to ISB.
With that being said, I love driving and I knew I would make it; I read a lot similar threads in here just to make myself familiar with the conditions and aware what to expect along the way.
We started off at 8AM and left for Multan via M3 and reached here in 4 hours. Road condition is better than I expected. We took a break here for lunch and left for RYK via M5. Again the road condition is phenomenal and we stayed in Plaza Inn Hotel overnight. On the next morning, we left for Sukkur via M5 again; needless to say it is fantastic. Now from Sukkur to KHI you have to stick to the highway which isn't bad I'd say, but not as good as motorway either. You gotta be careful here as some of the patches are one-way with all the heavy vehicles rolling in.
Alhamdolillah we finally reached here in Karachi safely by 9PM. It was my first ever longest drive alone and I thoroughly enjoyed it. 
