Four per week seems like it might be a lot for one cat.

Every cat is going to do it now and then - if nothing else, they get fur in their throats and have to cough that up.

But I had a cat that had food allergies and inflammatory bowel disease (that cat has passed away, but now we have another cat that also developed IBD…sigh). That cat did a lot of throwing up. We have three cats now, and I’m cleaning up fewer messes than he generated alone. I miss him a ton, but I don’t miss cleaning up the messes.

But, my suggestion is that you note what’s in the vomit - are you seeing fur? Undigested food? Digested food? Or just bile? And note the frequency. And then talk to your vet.