Going back to your original question:
"Is it reasonable to change the ball joints and control arms in 2-3 hours if supervised?"
I would say that it depends on how many of you and the combined experiences.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)