To upgrade from s24 ultra or not - definitive guide to trading in each year?

Hi,

I hope others can kindly make this a quality post for all.

I have bought the s21 ultra and upgraded every year since.

I think the s 22 ultra was my favourite (the zoomed in pictures ever since have not been as clear).

I am in Australia. I figured trading in each year maximises my trade in value, but how much is the difference per year say if I keep this phone another year?

Am I better to hold this phone and await the s 26 ultra? How can I tell?

For me, tips to others are to check whether your accessories are compatible. E.g. I have bought the otterbox defender case or similar each year, plus screen protector.

My s 24 ultra is as new, but I hoped for a more advanced phone. Not seeing the benefits to upgrade at this point, but grateful for experts or others to give their views.