Hey, Vern - While I see your point, I wouldn't restrict the benefits of being melodic (viz, a singer, or in my case a whistler) only to the chrom' player.
For
example, akin to what to Mojo and Mike were talking about, I find that
playing songs for which I ~know~ the tune by heart in various positions on a
diatonic to be some of the best exercises I know of. For me, playing scales
really didn't help me learn to nail specific bends (e.g., 3D' vs. 3D'' vs.
3D''') as well as playing songs in which I ~knew~ in my bones what the bent
note should sound like 'cuz I'd heard and/or whistled a tune dozens, even
hundreds of times. Familiar folk, campfire, and even kid's songs that
everyone knows played thusly make for great diatonic practice fodder, IMO.
Vern Visit my harmonica website: http://www.Hands-Free-Chromatic.7p.com