>>96512481
Have you read much in the way of first world war accounts?

This is a decent one
https://www.youtube.com/watch?v=ARD-xXwKI3A

I collected a few WW1 audiobooks together here:
https://www.youtube.com/watch?v=ARD-xXwKI3A&list=PLYIx7audKFzw4SyvD7Kq3QCjt1BhdEoCB

What I remember is that artillery could be relatively precise - if you wanted to hit the enemy trenchline, you generally did thanks to observers, or it being a static defense that probably hasn't changed position in a year or so.
While artillery is falling, everyone is in their dugouts, or hugging a crater, no one moves (unless they're currently on the attack and the artillery is a creeping barrage supporting them).
Then once the artillery clears, people immediately get back into their positions and man their guns.

This is why creeping barrages became so necessary, as you need a physical / smoke barrier between you and the enemy and to hit the enemy as you're walking up to his trench in order to effectively suppress MGs and rifle fire.

If it's a hex game I'd say any hexes targeted by artillery are suppressed, and if they are in a trench or shell crater, they'd take casualties on a 6+. If they're in a dugout they take no casualties, and if they're in the open and advancing, they'd take casualties on a 3+, although they'd immediately hit the ground after the first barrage, so would be like 5+ after the initial fires.