There can be confusion about PUPD.
In the books Tracy refers to PUPD as part of shush/pat. When a baby is young you use shush/pat and of course if she is crying you pick her up, calm in arms with shush/pat until totally calm and drowsy then put down in the cot and continue to shush/pat. It *is* picking up and putting down but there are no timings, no limits to how long you hold her, shush/pat is used throughout and LO can be patted all the way to sleep if needed as this is gently weaned in stages.
On the forums we distinguish between PUPD and shush/pat a little differently. With shush/pat being the go-to method (including though the picking up and calming in arms aspect and putting down when calm) and PUPD being a little different, a last resort method as bec said. PUPD (in the books and on the forums) has specific age linked timed aspect where LOs are put down again even if still crying, you never leave LO and you pick up as many times as needed but the method does not use the shush/pat aspect and becomes tougher - young babies can lose too many calories by the continued crying which can come with this type of PUPD.
There is a FAQ which details the age differences with PUPD but I'm having connection difficulty at the moment so can't link it.
Hope this helps to clarify.