When spaceing headers for a 2x4 stud wall you use a 1/2 piece of plywood.
What is the best way when using 2x6's for studs
Thanks for your time!

Not sure what you are asking. A header is set on a stud(s) and that's it. Are you asking how to fill in the width of a header from inside of wall to outside of wall I have never heard of "Spacing" headers on any job site.

Please explain more so all here can assist

OK, If you are using2x6s for headers over a door you ues 2 of them with a 1/2" piece of plywood between them to make it 31/2" wide, the same width as the 2x4 studs.
So if I am using 2x6s for wall studs what is the best way to space the 2 2x6s apart so the header will be 5 1/2" wide the same as the 2x6 studs.

If you take 3pc 2x6 and by the time you nail them together it will be 4 3/4" not 4 1/2" Then a piece of 3/4 ply sandwiched between them.

The 1/4" diff is simply the more wood you nail together the more you loose in the " perfect" 1 1/2" increments