I am sure it could affect things, hair length as said, a band with limited freedom or tied poorly could affect presentation (Daves advice on how to secure the band but maintain its freedom is spot on imo and how I do them-cocktail stick for me). Little tip on that aspect too, is to pull on the tag end of the figure of 8 loop, rather than pull the loop/band/bayonet/spike when settling the knot, as that tends to result in a bigger loop than you need-critical if its a plain hair loop. Wetting the line before tucking down any knot-if the loop is tied poorly it will kink and cause the hair to creep around the bend/shape of the hook. Too thicker line, preventing natural movement of the bait.
You do see also about a hook, once tied having an 'aggressive angle', ok, but too aggressive and I think it takes away hooking potential and essentially masks the hook, especially on exaggerated in turned point hooks. So right hook for the job comes into play.
It's the business end of any rig/set up so crucial that its right. Tie all of my own and for others. I think back to when hair rigging first came popular and some of the ready mades and by some of the popular manufacturers always had me concerned about hair length- way too long for what they were intended for and when the range went. 18 on 5, 16 on 6, 14 on 7, 12 on 8. I felt that the larger hook sizes I needed weren't on strong enough line. Subsequently and until I started tieing my own, I was having to use too larger hook just to get the right breaking strain of line. I believe ranges are better now in that respect, but to get exactly what I want, I just do them.
....Always room for improvement in what ever we do as anglers.....You're asking the right questions, and experimentation is key, but not to the extent you wind up driving yourself around the bend with "ifs and maybe's'......Do what works for you, in my experience, is always the way to go. 
