Implication of application location

For WP/HSMP it goes to Sheffield
For ILR it goes to Durham
and for Naturalization it goes to Liverpool

What is this implication of the location.
Does the Sheffield files, go to Durham?? and then Durham to Liverool, for the next stage of the process????

It also seems to me that different criteria are applied at each stage or more so their interest is focused in a different way.
For example the WP, if you are still needed for work, HSMP today its about the amount you make among other things, and can continue to work to get your extensions.
For ILR, that you were legally here for 5 years and can still maintain yourself and continuity of residency
For naturalizations, your residency, your character, your references.

What do you guys think?