300 rd an hour, umm, sorry. That doesn't include breaks, refilling your primer and component trays, or switching calibers/powder measure, etc. I've seen a guy doing 1 round per 10 seconds, but everything is already set up, and he has the cases and bullets lined up and ready to go.
There's no doubt a turret is faster than a single stage. But when you're switching between multiple calibers, that difference comes at a cost of either a powder drop for each caliber plus the extra storage space. Or the extra time of removing, reattaching, and readjusting your powder drop every time you change caliber. This is why I threw my Perfect Powder dispenser in the closet, never to be seen again. And even if you have a dedicated powder drop, there's no way it's "at least 3-4 times faster."
And FYI, the Safety Prime is actually slower than priming on a Lee Breechlock by hand. You have to stop at the top of the stroke to use the Safety Prime. On a Breechlock, you can put the primer in while putting in the case, so there's no wasted time.
I can load a pistol round from start to finish every 10-12 seconds on a turret(yes i have timed myself).
I've filmed myself using a Lee Breechlock. I put the links at the bottom. The seating/crimping step wasn't filmed while "in the zone." If it had been it would be less than 4 seconds per round. (And when I'm in the zone, I'm looking at my box/tray of bullets while pulling the lever, deciding which one will be easiest to pick up, next!) Total estimated time is about 13-14 seconds per round. I know there's more time getting the stuff in place, and whatnot. But still, compared to 10 seconds per round maximal turret speed (also not including setup), it's not vastly slower. Certainly not by a multiple of 3-4. Even if crimping in a separate step, that only adds about 2 seconds per round, done the same way as the flaring in the second vid.
Sizing/priming ~ 4-5 seconds per round
http://s688.photobucket.com/albums/vv241/gloob27x/?action=view¤t=loading001.mp4
Flaring ~ 2 seconds per (note, if I was better at math, "I could probably do these 100 cases in closer to
3 minutes!")
http://s688.photobucket.com/albums/vv241/gloob27x/?action=view¤t=loading002.mp4
Charging ~ 3 seconds per
http://s688.photobucket.com/albums/vv241/gloob27x/?action=view¤t=loading003.mp4
Seating ~4 seconds per, not reflected in this video.
http://s688.photobucket.com/albums/vv241/gloob27x/?action=view¤t=loading004.mp4
The big advantage would be that you could have done all of this in less than a hour with the turret instead of sizing and priming one day then filling, seating and crimping the next.
The larger the batch you do on a single stage, the more efficient it is. So yeah, that's one advantage of a turret, if you load in small batches. I don't care if I get my first finished round today or tomorrow. It's the overall work involved per round that matters to me. So I wait until I have a crap ton of cases, then size/prime them at once. Then I can take my sized/primed cases and make however much of it into finished ammo, depending on my needs.
And space matters to me. I load 4 different calibers regularly (using 2-3 different powders for each caliber) and an additional 2 calibers, less frequently. I have all my various scoops in an Altoids tin, which is a bit smaller than 4 different turrets with a powder drop on each one, and no time spent fiddling with the dispensers for different loads. If I'm going to go that far, why not just go for a progressive?
IOW, a single stage press has a significant space savings advantage compared to a progressive (powder dispensers and tool heads). A turret does not. A progressive has a significant speed advantage over a single stage press. A turret does not. A turret is just a (semi)progressive for cheapskates, as far as I can tell.