Rocker arm torque in 2 stages?

2003 Windstar. 3.8.
I am going to be changing head gaskets. I like to read up on things before I do them so as not to make a mistake.
One thing I don't understand is the torque for rocker arm nuts.
Put cylinder that you are working on to TDC. Install pushrod then rocker arm. Then torque to 44in/lbs then 2 stage torque to 24ft/lbs. at what point do I do the 2 stage 24ft/lb. Do I install all rockers at 44in/lbs and then go back and retorque them to 24ft/lb. each time rotating engine to TDC on cylinder I am working on. Why 2 stages? Does the nut have to seat itself before it get final torque. If I can do stage 1 and then stage2 torques one after the other how long to what between the 2. I don't understand.

I think they want each piston at TDC on combustion stroke so that the valves are closed ... and then torque THOSE two nuts in two stages. That's a lot of co-ordination along with crank turning. I am not so careful ... I just do the "torqueing" in several incremental steps around the heads....no matter where the crank position is. I figure if I do it in small enough steps ... all will be good. I have over 200k miles on the 3.8 I've rebuilt ... 422k miles overall. (But I'm not recommending ... just saying what I do.)

If it were an air craft engine; I would take a different, more cautious, approach.