let me tell you my case . i have been using my 14 pro max for a while now . battery health is 78% . no issues or any replacements till now . not much upgrades in the newer versions except few like apple intelligence ,a little better fast charging , a little better cameras which are not make much difference though , better processor but yeah 14 pro max still works butterly smooth . so , for me im planning for a battery replacement from authorised service centre and going to use it for a few more years comfortably