My experience is not at all like yours. On my main home machine (Mac Studio), every photo downloads immediately. I have it set to always "Download Originals to this Mac". This is the machine that I back up locally (Time Machine) and to the cloud (Backblaze). I also created a clone which gets updated every night using Carbon Copy Cloner.
Everything that I do on any of my other machines... my primary laptop (M1 MBP), my secondary laptop (Intel MBP), my 13" iPad, my 11" iPad, my iPhone 15 Pro... all of that instantly syncs back to my Mac Studio. Hence... everything gets backed up in real time.
BTW: I do NOT consider iCloud or other syncing services to be "backup". Yes, in most cases, it probably is the most convenient method to recover from a disaster... but a true backup solution (ex: Backblaze), allows you to turn back the clock and recover from a pre-disaster state.
BTW: I have owned several storage arrays (NAS, Home Server, Thunderbolt RAID 10) and every one eventually died on me. This was NOT a result of losing a drive. In all cases, the actual storage array box died. I will never buy another one... they are obsolete technology. Cloud storage is the answer.
My goal is to have one place to automatically store 100% of my data (my Mac Studio)... back it up so that even if my house burned down, and I lost 100% of my machines... I could walk into an Apple Store, get any new equipment, and be up and running in very little time, while losing zero data. I believe I have accomplished that.
/Jim