I might have agreed with bonding when I worked for NATS, but now that I know the company has no more loyalty to its staff than those who leave have for NATS, I think differently.
I stayed considerably longer than 5 years and when I wanted the option of returning, the company preferred to hire those who cost less, hence a severe shortage of controllers at my old locale where those with 2 years of tower-only experience at Little Hampton on the Wold have trouble validating...
The company wants your pension, your days off, your lunchion vouchers and a lot more besides. When they earn loyalty, they can have it. Now, not so much...