I must be at the part of the game where I don't have any good weapons yet. The arrows I have do nothing but make the machines angry at this point. It isn't hard, just tedious. While I am pumping 20 arrows into something to kill it, 5 other robots just wandered in and are now all attacking too. Then it is run, hide, repeat. Maybe I'm doing it wrong, or just haven't unlocked the good gear yet. Most of the weapons I make are pretty terrible. It takes 20 arrows easy to take down anything big, and usually more.
Sounds like something is going wrong, if you are slinging 20 arrows into an enemy, and then you get ganged up on by 5 others, so you have to run away and come back, over and over. Yeah, that doesn't sound like fun.
Let me see if I can help.
1. When you're early in the game, you're only supposed to be taking on the lower-level enemies -- Walkers, Striders, Grazers, Scrappers, etc. You should be able to take those out with two or three well-placed shots or other strategies. You're not supposed to be capable of handling medium-level enemies like Bellowbacks, Sawtooths, Snapjaws, Ravagers, etc (to say nothing of the harder enemies). Those things are supposed to scare you, because they are way more powerful than you, and you are not equipped to handle them. If you try, you will end up badly outmatched. So maybe you are trying to take on enemies that are just too tough for you?
2. I get the impression you are just engaging the enemies with bow and arrow. I say that because you keep mentioning it. The combat works best when you are using all the weapons in your arsenal -- traps, tripwires, ropecaster, grenades, etc., not just bow and arrow (although you use a lot of that, too).
3. I did a lot of stealth. I really enjoyed that approach in this game. You might want to use more of that, if you're not already. It helps thin the herd considerably. And taking the machines down feels satisfying.
4. We've mentioned this before, but there are good strategies and ineffective strategies for each enemy in the game. If you're finding yourself plunking 20 arrows into a creature, running away and repeating, you're either 1) trying to take on an enemy that is too advanced for you right now, or 2) not using the right strategies.
5. It may also be a matter of personal taste, to some degree. I enjoyed the process of coming at tough enemies over and over, making repeated runs, until I finally took them down. I remember the first time I took down a Bellowback. I think I spent 20 minutes on it -- plunking a couple of arrows into his tender spots, then hiding and hoping he didn't sniff me out. It felt good to finally get him, though. But to you, maybe that process is tedious. (Later in the game, I could make much shorter work of Bellowbacks, but the first time was tough.)
I hope that is helpful. Ultimately, though, if you're not enjoying it, just drop it. No game is for everybody. Horizon hit all the right notes for me, but it might not be your type of game. Different strokes and all.