You can keep shooting the optic lens the way you've been doing it all along,,, or you can adjust it so it benefits the down range horizontal & vertical.
Nothing like having Firearm, Ammo, optic Scope and Shooter all dialed in on a level playing field.
As some of us age, our eye sight changes, so fine tuning "might" need to be addressed once in a while.
These are the tools I bring to the range when setting up a optic that I choose to shoot long range.
1- A Blue Sky Day.
2- A coloured felt marker.
3- Good quality bypod.
4-Firm bunny ear rear bag.
5-Distance of 300 to 1700 meters or beyond.
6- Large targets with mileage bars.
7- And as much time needed to get things sorted.
Funny that we allow what ever time we need to get things right for long range shooting, yet "alot" of shooters don't take the time to fine-tune thier personal optic lens which can benefit us "More" then chasing smaller issues that benefit us the least.
Of course I only share Earl Hines concepts of "Parallax Adjustments" with those that choose to chase this part of the dragons-tail once and for all.
This is not saying that there aren't other ways to fine tune the optic scope as well.
https://www.longrangehunting.com/articles/what-is-parallax.1175/
Foot-note added:
1- I start at 300 to 400 meters since it allows me to see the cross-hairs move off target with rifle firmly planted.
2- If I don't see the cross-hairs move that much,,, then I manipulate the focus and parallax so I can move the cross-hairs to maximum amount.
This would be 12" to 17" inches from the target bulls-eyes out-ward to the edge of the target. Target placed at 3 to 400 meters.
3- I'll share more on this for those interested in getting this sorted,,, again,,, for those that choose to correct a optic lens for their own personal shooting needs.
PS: If a person chooses to shoot close range, is not fussy about spilling hairs at 25 feet to 200 meters,,, then carry on.
Those that choose to push the limits of 300 to infinity shooting meters "could" benefit from this.
I have 3 F Class optic scopes ready to go,,, and 1 for my 1700 meter stuff.
It's like a work of art sorting out the things that benefit us the most as we address the small things at a later date.
A proper tuned optic lens is a major thing in my shooting sports.
More wrong then right I hope. Ha
Don