It entirely depends how long you keep your devices. I try to keep my iPhones until release year + 6, so I would need the price of a previous version to be reduced by more than 1/6th on a new version release, which is usually not the case.
Similar to cars, most depreciation happens in the first year.
So owning a device for 6 years between age 1 and 7 will generally have a lower cost than owning a device between age 0 and 6.
For Apple products it’s generally feasible to effectively buy first hand devices aged 1+ because they’re still available for sale (at least in some retailers) after a new edition is released.
That’s a good strategy with most things that aren’t prone to mfg variability . For cars having a launch version there are a lot of initial manufacturing defects that need to be worked out.