Patek Philippe

With a high-end manual wind chronograph, you have none of that blocking the view. You are able to clearly see all the components individually and how they even function through the caseback, as you activate the chronograph. All these components have to be visually elegant in design and finished to a high degree to give the appeal, so they are usually expensive to produce. Typically you'd see lots of anglage, straight grained steel surfaces, some black polished parts like the column wheel, and some elegant curved detent springs.

On a related note, bear in mind there are also two general categories of chronographs. Horizontal clutch, and vertical clutch. To put it simply, high-end manual winds chronos are typically of the horizontal clutch variety - the parts are laid spread out across the movement which gives it more visual impact. The Lange Datograph, Patek 5170/5070/5370/5204/..., Speedmaster Moonwatch with 1861/1863 movements etc. are all horizontal clutch. Meanwhile, a vertical clutch has most components stacked - you guessed it, vertically. This has less parts visible through the caseback. Examples are the Omega 9300, current production Rolex Daytonas, Grand Seiko chronograph, Patek 5960. Usually, since these movements already don't have much mechanisms visible, these are equipped with automatic rotors to make them more practical to use (couple that with the technical advantages of a vertical clutch vs horizontal - but I digress). 

2. Both honestly. A quick history off the top of my head recalls that split seconds/rattrapantes used to be categorised as a "Grand Complication" - they are not easy to manufacture due to the finer than normal tolerances involved than what was already complex a standard chronograph (which were mostly horizontal clutch back then. I only recall Seiko or Frederic Piguet movement that did vert clutch during those days). It was only until Habring came about when he designed a simplified rattrapante while at IWC that they became much more accessible to the general public.

However, to construct a traditionally designed split seconds chronograph today is still not much simpler, and still a technical marvel. At this point since its more of a matter of prestige, they are constructed usually over horizontal clutch chronographs because there is so much mechanical visual appeal. Also, since the layout of the components of a horizontal clutch chrono are spread over the movement flat, it is easier to simply construct the rattrapante module on top of existing chronograph like a tower (see 5370 or Lange Double Split versus 5170 or Datograph). Here is an example gif animation that shows how similar a rattrapante is basically built upon a standard chronograph as a base https://i.imgur.com/4od8Rkq.gif

I'm no watchmaker, but if I had to guess why its so much more difficult to do is that first, you know have to deal with an extra shaft going through the centre of the watch, so there are four hands on the centre of the watch (hour, minute, chrono seconds, rattrapante seconds). The thinnest shaft running through the centre, the rattrapante seconds, I heard are as thin as a human hair. The extra module of a rattrapante when activated, imposes extra load onto the mainspring which means the base movement requires enough torque to power it (otherwise, the usable power reserve I imagine is significantly shortened). All this requires quite abit of adjustment to make them work right I reckon. Also, usually a rattrapante would also be activated by a column wheel - that means two total in a typical high-end rattrapante.

3. Probably an hour subdial is not included to prevent too much clutter on the dial. Most people usually would not use the chronograph to time things beyond an hour in practice...However, of course there are some popular chronographs that have hour subdials such as the Speedmasters (both the 1861/1863, and the newer 9300 models)

Technically for most chronographs, the chronograph seconds has a little finger on it that "flips" the chronograph minute counter by one space forward when it finish revolving across 60 seconds. To have the chronograph minutes having a finger to do the same to a chronograph hours counter would impose quite alot of load onto the mainspring. So instead, most chronographs with hour counters just directly couple the chronograph hour counter to the mainspring barrel. It constantly slips - since the mainspring barrel turns so slowly - but when the chronograph is not in use there is a lever which holds down the chronograph counter stationary so it points to 0 hours. When you activate the chronograph, the lever releases and the hour counter starts rotating slowly together with the mainspring barrel.

Regards,

skyeriding

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