For a bungalow GF extension and conversion/addition to the loft ....
I'd probably spend 2 hours on site and 50% of that would be me just chit-chatting about anything
To draw them up would no more than a day for the existing and most of the proposed, but lets say 1 1/2 days.
Then they would be ready for client approval.
But, I like messing, so will spend perhaps another 1/2 day or so doing some 3D views and renderings.
The new planning application form will take probably an hour.
Now I don't charge hourly rates for drawings, its a fixed fee. And I don't charge extra for chatting on site, revisiting the site, moving things about on the drawing for the client, or doing some nice graphics which will make a bland extension look nice for planners and get the permission. And I know that most of the other local plan drawers charge much more for much less
But for a run of the mill proposal such as this bungalow, with some bog standard drawings I'd spend no more than two days - that's 16 hours. And thats me - I'm not particularly fast, I may get sidetracked (normally to this site) and I draw too much detail. So I would expect a technician who does this as his main job to do something like this in less time. And even less time if he has a template from a similar previous job. What will these two visits be ... 2/4 hours each? That comes to 24 hours tops
So IMO, 50 hours is way too much time, what ever the hourly rate. How long are the b/regs going to take?
You should have agreed fees at the start. Yes, some things may not be known, but the guy should know how long it will take him to do drawings to planning stage and should have given a very close approximation of how much time he will spend on the plans or how much the plans would cost to get to planning stage