How tight to set solid lifters

It probably has been asked before but let's review the age old question of how tight should the gap be on setting solid lift gap. Clay smith cams tells me 018 thousands! After watching an episode of Power Nation Pat Topolinski states that changes if you are running aluminum heads on a cast iron block (Yes I am) He stated it should be tightened up by about .004 which will put me at .014. So not to cause myself any problems I need to ask what are you running/ setting yours at.
My set up.
Caly Smith flat tappet cam
American made lifer's (From them)
Smith brothers push rods
Harland Sharp 1.6 roller rockers


Set mine at .018 for start up using the E.O.I.C. method which might be controverisal all in its self .... I dont want to start any big debate like what kind of oil do you run......
No I have not done the hot setting ....
Please advise Texas Red
Why is this so crucial these days ? back in the old days the myth was ......set loose for more top end power or tight for more torque or vise versa.