Are you talking about insert type replacement or replacing new construction windows with new construction windows?

Regular replacement , no flange.

Shims are required only where necessary to insure the insert unit is plumb, level and square (for proper operation and weather tightness). For years shims were only available in wood (wood shingles normally). In recent years plastic and or composites have been used and either is fine.

+1. The use of shims is going to vary from window to window. MWM is right on... It also depends on how tight the window fits, use of spray foam or not, how many fasteners, jamb jacks, etc etc. Not really a hard rule one way or the other.

Most windows have built in adjusters that almost eliminate the need for shims?

Depends on how many jamb jacks and how out of square the existing window frame maybe and where it may be out of square. Shims may still be necessary.

Jamb jacks ?

You can see the jamb jack here in the center of the window.

It is a small screw that is accessible from the jamb (i.e. glide path of the sash side) for adjustment to adjust the tightness of the window.

This is for HomeSealed...