Each time u changed phone, u have to link new devices for every bank and TnG you got. The hassle is enough to spoil your mood for at least few days or even a week depending on how much hassle involve for each bank.

I change phone roughly 2-3 years once, maybe i may change soon?

How about reset phone? Will it able to detect as same phone and allow login?
Idk coz the linked device page only show phone model and activatio date. Is it linked to imei?