Britney has released a prominent and significant tour during the 3 phases of her career: her early career (dream within a dream tour), middle career (onyx hotel tour), and later career (circus starring britney spears).
She has also released at least one huge prominent global smash during the 3 phases of her career: early career (baby one more time / oops I did it again), middle career (toxic), and later career (womanizer / scream and shout).
In the albums department Britney has released a musically important album for her own career with impact on pop culture and pop scene in her 3 phases of her career; early career (BOMT / OIDIA), middle career (In the zone), and later career (Blackout).
Additionally she has a #1 single and album in 3 different decades (90s, 00s and 10s) in most countries around the world.
Longevity
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@ Trafalgar Square 
, the thread got really messy and the mods don't close it
