What differs, in my experience doing two extremes of brewing--75mL gaiwans gongfu cha, vs filling a thermos full with a series of larger infusions from my kamjove infuser--is that the shorter brewing allows certain flavors to stand out more, that diffuse out of the tea at different rates. The all-in-one will give everything mixed together, the many shorter infusions may be more floral then spicier than sweeter or fruitier etc etc.
And both are perfectly valid ways to enjoy your tea.
I use my 180mL teapot principally when I am filling the thermos, but sometimes I want fewer larger brewings, and just do a semi-gongfu cha. All ways can be good ways when the tea is good.