I've got the current level 31 build
Level: 31
Strength: 18
Agility: 21
4 Powerstrike
6 Powerdraw
7 Weapon Master
7 Agility
2 Riding
156 Archery WPF, 68 1h WPF
And I'm looking at when I hit 32. I originally planned on getting +3 riding to maximize the number of horses that I can hop on mid-battle (I'm in no way a devoted HA), but after looking again at the horse shop, there's only two more horses that don't seem like they're very common. I'm considering instead going to just 4 Riding and putting the third point into 1 HA. I don't know if it would be worth it though.
This would also lead to (if I ever get that high) when I turn 33 I could have 7 Riding and 1 HA, or 7 Riding and +1 PS, as 7 riding is the ultimate goal so that I can always hop on a horse at random times in the battle.
tldr;
Is 1 HA noticable enough to be worth getting for the occasional HA ruse?