In the dev diary for "la resistance", the Paradox team in charge of the DLC mentioned how the spanish civil war was so long because for the most part it was just 2 people sitting on opposite mountains shooting at each other without actually managing to hit each other. Now I know HOI4 is not the epitome of realism, but this one statement is ABSOLUTEY 100% TRUE. The spanish civil war elongated so far for 2 key reasons. The first is that spain is mostly one gargantual mesetta surrounded by and filled with mountains, so basically the whole damned country is the maginot line. The second is that no side was willing to concede an inch, and both had a frankly absurd ammount of artillery. So basically it was ww1 tier getting stuck doing nothing for months on end. With most advances being made not by the front lines but by the guerrillas that raided each other's supplies.
So what did most soldiers do while the supply game happened? Well they sat just out of range of enemy artillery, shelling the enemy with their own artillery despite the enemy also being outside of their range, having the snipers battling it out, lookkng out for possible flankers and any developments, and basically doing absolute fucking nothing for months on end until either reinforcements broke the tie or someone ran out of supplies and the other side could push. Most of the war was just spent dicking around on base with absolutely fucking nothing to do.
This even got the soldiers the impression that it felt like both sides had to agree to attack each other before hand. Because usually spotters from either side could tell how the other was doing, so most of the time both sides where very much aware on when and were the enemy would finally attack if they did. Surprise was just not something the frontlines did at all. Which was most famously parodied by Gila on his monologue "is that the enemy?" Where he depicts a soldier calling the enemy to decide when to continue the war as he needs to go do something else for a while:
And then goes on to parody army incompetence in general. Gila btw fought for the republicans during the civil war. He was talking from experience (albeit with obvious exaggeration.)
And that's another thing. The "going to do something else"... is very much real. You see. Shit went so slow than soldiers commonly would just tell their squadmates that they were going to the city to buy cigs and rum and shit. And the mates were like "sure, here's money bring some for me" and the soldier would completely abandon his post, for days at a time, and come back to exactly the same fucking stalemate he left behind. Nothing had even changed.
We actually got a lot of poems, songs, art, comedy, variations on games, etc. Made by soldiers during the war due to how utterly fucking boring it was. And indeed, there is one thing that perfectly illustrates this. Here's a video by lindybeige:
On it he explains why british officers didn't duck in some time periods. Well a similar phenomena was spotted in spain. Let me paint you a mental image: let's say you're a rookie that just got conscripted and sent to the front lines. You're taking it seriously ducking behind cover watching the enemy. The snipers are dueling, the ground trembles with the shots of artillery, you see the land beford you constantly pummeled by enemy shells. Basically ww1 era trench warfare. And you look behind you, and you see a buncha vets doing the rounds with their morning coffee, fully upright, not even trying to cover anything above their waist, having a chat, right behind you fully exposed to the enemy. Well this was what happened the first day of combat one one of my family members. And he was far from the first one to notice it. Quite simply, the war went for so long, and the fronts were so immobile, that some soldiers stopped noticing the artillery and snipers. It wasn't a sign of defiance or morale thing like the british. Their survival instincts didn't kick in because quite simply they just got used to being under heavy fire like that... it just didn't matter anymore. So they didn't even register that they were meant to duck. And after a while it would become the norm for the whole base unless someone got hurt. Because for the most part, much like in that table game from warlord games, snipers were so busy dueling they wouldn't even try to shoot the other soldiers, and artillery had to keep itself out of range anyway so only way it was hitting anyone was by accident if a shell had too much power in it. This is why I say it is just straight up 40k imperial guard shit. You'd imagine having snipers firing all the time, the ground constantly shaking from artillery fire and the background repeatedly exploding into shrapnel is utter hell but people were stuck there for so long many of them just stopped caring altogether. Because they knew so long as both sides had supplies that shit wasn't moving, so why even bother really. It's basically an office job, but noisier.
So yeah point is, you'd think that being stuck in the middle of a ww1 frontline on a guerrilla-warfare driven conflict which is also one of the bloodiest conflicts in history would at least not get boring... you'd be wrong. Reality is just fucking weird sometimes.