Yes you need tiller.
This is because most bows have the arrow rest set above half way, not centrally when measured between the limb tips. So the bottom limb needs to do more work.
Now machine made limbs are usually made in pairs with no tiller built in - so it doesn't matter which way up you shoot them. Hand made limbs, such as Border, have the tiller built in to the limbs, so setting the bolts as equal (x turns out, both top and bottom) is recommended.
Not adjusting for tiller means you aren't necessarily getting the best from your very expensive equipment.
Stringwalkers in particular tend to have unusual tillers, sometimes even negative, in order to mitigate for the variable hand positioning on the string.
So yes. Take a little time and work out where the natural tiller should be for your bow and the way you shoot it.