As a young amateur I used a very large and heavy 4x5 German Reflex equipped with an extension bar and a 360mm portrait lens - I still have it. The idea was to keep focus and framing to the last second but it proved to be impractical because it required shooting wide open to see anything at all. The 'sshlunk' of the mirror and focal plane shutter was a notable feature and jarred the camera.
As an inexperienced pro I then made the mistake of buying a Plaubel Makiflex (it shot a square 4x4 on 4x5 film). The camera is in fact the neatest and probably the latest big reflex ever made (I looked at them all) and a great joy to own, but I soon found it impractical and it never earned what I paid for it. Impractical, because losing visual contact with the subject when the mirror went up and then having to change the film-holder and re-cock the camera did not help in directing the subject. Another awkward feature was the double cable release.
As a moderately experienced pro I found considerable happiness with the 4x5 twin-lens reflex Cambo and Grafmatic holders. It paid for itself a hundred-fold doing fashion catalogue work and portraits.
But that is like comparing the original Hasselblad 1000 with the Rolleiflex. Everybody used used two Rolleis (one was being reloaded by an assistant) rather than the Hassy for portraits because the Hassy's mirror had to be re-cocked.
Later, I had accrued experience and enough money for flash power to shoot a plain folding 4x5 with a press shutter at f32 (albeit with the subject's feet nailed to the floor), focus and framing was no longer a big deal and I never lost eye contact with the subject again.