From a Plank article written by George Kreik:

Update - PLEASE NOTE: THERE HAS BEEN A CHANGE IN THE MITER SAW INSTRUCTIONS

The requirement for multiple passes when cutting 3⁄4 inch or greater stock is only required on miter saw 18. The requirement no longer applies to the other miter saws.

Miter Saw 18 ONLY

All cuts of stock greater than 3⁄4 x 4 inches shall be made in at least two passes with the blade stopped before the saw is pulled back for the next pass.

From Updated Miter Saw 18 Story Board:

Cuts wider than 4” require slide motion to cut.

All cuts of stock greater than 3⁄4 x 4 inches shall be made in at least two passes with the blade stopped before the saw is pulled back for the next pass.

Proper sequence for cuts:

1) Pull saw out. Bring blade to full speed.

2) Bring saw down to cut approximately 1⁄2 inch of the stock.

3) Holding that height - push saw all the way to the slide stop (slow and steady motion).

4) Hold saw until the blade stops completely.

Repeat this process until the full cut is made.