Select the Draw a line tool
Enter the angle you wish to have for the stringer > draw the stringer
Leaving the modifier panel open > enter the angel and the length of the tread in the modifier box
Select Offset or move line(s) by an absolute parallel distance tool
Enter the distance for the tread offset, ensure copy is On, Constraint Off
Left click to highlight, right click to set the location, left click to place the next riser (this can be performed quickly)
Select Draw tool draw 2nd stringer down opposite side
Select Trim (clip) lines to closest intersection
This video starts drawing a line at an arbitrary angle
Once a line is drawn (stringer) > select Draw a line perpendicular to another line from the draw tool drop down
Click Draw a line perpendicular to another line >Highlight the stringer line
Enter the length of the tread in the modifier box> click end of stringer line to place perpendicular line
Select Offset or move line(s) by an absolute parallel distance tool
Select the distance for the tread offset, ensure copy is On, Constraint Off
Left click to highlight, right click to set the location, left click to place the next riser (this can be performed quickly)
Select Draw tool draw 2nd stringer down opposite side
Select Trim (clip) lines to closest intersection