Greg, It takes about 3.3- 4.0 hours per Kilo. That one above was about 2.1 kilos from memory. The time till done can vary I just pull it off when its done.
The bigger the joint the more it takes the get the internal meat temp to 80 deg
A large, say 5kilo but of beef would take up to 20 hours
Also I think the larger joints tend to slow cook beter then pissy little 1.2 kilo ones.
The smaller ones tend to dry out a bit.
I did the cooking and I get the shank No one argues that in my family
But I then feel selfish and calve bits off to share around and the kids usually get it in the end after my wife does that "Thing" when she starts on about the muscle meat not being good for my heart She knows how to manipulate me I think