Oh boy, what a can of worms...OK, here goes...
I've done it three times in my life, the first two were fast and easy the third was a doozy in terms of wasted time, energy and money...but I got there...
The first was back in 1990, I was still a kid digging metal stuff, I had picked up the guitar a year before that so, no real knowledge, no access to information out there (no internet, the dark era), just a few magazines like Guitar World etc. My first guitar was a super strat (HSS) knock off , totally $hitty pickups. I didn't care much about the middle and neck but I needed a good bridge pup (=back then that was one with a buttload of output, lol). Well, I saved some money, entered a local store and bought a Dimarzio humbucker pickup (I don't remember the model, one half had a bar, the other half had the normal 6 string poles and the bloody thing was pink!). That was it, first and almost random try, I was happy until I stopped digging metal.
The second was a few years after I bought my first decent guitar, a MIA '57 RI strat (57/62 pickups), that was in 1994. In terms of information accessibility nothing had changed (still no internet) but it didn't matter, I was flat broke anyway and more interested in playing and recording than anything else. Fast forward to around 2006, now I could afford a couple of sets of pups to get closer to the sounds I was after and I had already done my research (thank you internet!). And along came a set of CS69s. That was it, the next couple of years I bought another two sets for my other two guitars and I was happy for a dozen years until, well, I wasn't...
By the end of 2019, I knew something was very wrong with my sound...I had changed, my tastes had changed, my playing had changed...I didn't love or even like scooped sounds anymore, I wanted more mids and a fatter sound overall...So, could I have become a humbucker guy after 25 years of playing and loving strictly SSS strats? In terms of bridge sound I was pretty sure I already was a HB guy, I always hated the traditional strat bridge clean sound anyway, personally I only used the bridge with fuzzes. But I wasn't playing "dirty" anymore. OK, then, the first batch was four Dimarzios, Fast Track 2, Tone Zone S, Pro Track, and Air Norton S. The Fast Track 2 just wasn't for me, way too hot and middy for clean sounds. I used the rest as bridge pups in my strats.
That was the easy part...now what about the middle and neck positions? I thought, OK, I might as well just go with hotter single coil voiced pups so I bought a couple of Cruisers and Fast Track 1's, one pair for each of my "active" guitars. Right? Now, I stopped touching the guitar I put the Cruisers in a couple of weeks later (that was clearly a sign I didn't like the pups). I liked the Fast Track 1s better but I was still stuggling...I started messing around with settings that I had never messed with before on my AF2 and AF3 later on.
Something wasn't right...I had already tried the Air Norton S in the neck position some time ago, took it out a few seconds later, too boomy for me. Then one day I wanted to rewire my two active guitars, so I thought, I might as well start with the guitar with the Cruisers and the Pro Track in the bridge. So I go, OK, let's disconnect everything and try the Pro Track in the middle and neck, and if I am not in the mood to assemble them all back, no problem, my other guitar was my favorite anyway. Well, you should see my face the moment I tried out the Pro Track in the neck/middle positions. That was it! It's official, I am a full humbucker voicing dude! I got rid of the Cruisers and Fast Track 1s, ordered another 3 Pro Tracks (after that I stopped using that Pro Track in the bridge position, I prefered the Tone Zone S and Air Norton S) and Bob's your uncle, the rest is history...
Come to think of it, that last journey was my fault for being that long and I was lucky, I know a lot of people that go through a dozen or so pickups (for each position lol) and they are still not satisfied so...
I just hate the pickup rabbit hole though, I really hope my tastes never change again...