I've never run AL for appliances, but seen it a bunch. I guess my early bosses thought it was just easier to keep a roll of 8/3 in the van.I started out in the field in 1982. We would run 6/3 SE aluminum for three wire ranges and 10/3 romex for three wire dryers. The egc on the dryer would be doubled up with the neutral or screwed to the tomb stone chaise.
About 10 years ago I worked a short stint for a hack contractor, trying to save every penny he could, no matter how. I did a finish first, and was horrified to see 8/2-g to a range, from a subpanel no less, and the bare landed on the ground bar