IMO it depends on how confident you are in your cleaning methods.
For a lot of years I did the full tear-down after each use. This was because my first brush (a Paasche VL) had nooks and crannies in the paint path that would never come clear from flushing alone. Plus I used it for a variety of different paint types: enamel, acrylic, lacquer, etc., and that necessitates full cleaning to prevent cross-contamination.
When I first got my HP-CS, I carried that habit over. I eventually dialed it back to mostly only flush cleaning it between most uses. This wasn't because of laziness, but just because I'd gotten enough experience to know how to flush-clean it well enough.
I still do a tear-down cleaning every 5-10 sessions, or if I'm switching paint types, or if I'm not expecting to use the brush again very soon. I only remove the head/nozzle as part of a tear-down, or if I suspect there's something stuck to the inside. I don't soak anything unless I have reason to think I've got something gunked in there hard, which has gotten rarer and rarer as I got more experience with general maintenance (this includes better painting habits to prevent clogs and bad paint or bad paint/solvent combos).
THAT SAID, there is one extra trick/step that I do when flush-cleaning that others apparently don't, but I consider essential. The one big place in the HP-CS where paint can lodge where flushing won't get it out, but it can still contaminate subsequent colors, is the needle passage between the packing and the cup. If you don't get that sufficiently clear, it'll seep the previous color into the new paint in the cup. The way I address this during flush cleaning is by filling the cup with solvent, then sticking a pipette into the cup so the end is touching the needle right where it enters that back passage, and pump a few times. This blasts fluid perpendicularly across the opening, creating a Venturi effect that cycles fluid through that back channel. Clears it out quick & easily without having to take anything apart.
I generally prefer to remove needles from the front if I'm cleaning immediately after a paint session. This is because I've observed that even with a good packing seal, the needle will still drag a little bit of wet paint with it into/through the back of the brush. However, if I'm removing the needle when the inside of the brush is clean and dry, then I'll remove it through the back.