I use Manual almost all the time with the 8speed Automatic.
I prefer to keep engine speed low and to be in the right gear depending on actual road conditions, and the road conditions that I see ahead of me.
E.g if I am in 5th gear and conditions are that I would go to 6th, but I see a bend in the road coming up, rather than going to 6th and going back to 5th in the bend, I keep it in 5th.
When going down slopes or slowing down for a junction, I use it for engine braking. Goes very smooth with the six cylinder I have. But between 3th and 2nd gear, there is a big gap. So I have to watch that I do wait going from 3rd to 2nd, until engine speed has gone down enough.
In situations with dense traffic, where I have to concentrate on the traffic, and where many gear changes are expected, I put it in automatic.
Even though I grew up with manual and like to drive mostly in manual, I like the automatic for pulling away from standstill, for preventing rollback on a slope.