I spent a week in Switzerland in July and only encountered one delay, which was on a Railjet, albeit the cause of the delay was in Switzerland. It was major disruption too, but handled better than I’ve ever seen equivalent disruption handled in the UK.
The Railjet had departed Zürich HB as usual but only made it as far as Zürich Wiedikon before being stopped. Can’t remember exactly what it was now but it meant that the usual route to Sargans was blocked.
Within 10 minutes of stopping at Zürich Wiedikon the train had left again in the reverse direction to take a diversionary route to Buchs, running non-stop through the low level platforms at Zürich HB and then via Winterthur, Amriswil and St Margrethen. Arrival into Buchs was about an hour late, the diversionary route skipped Sargans so for those headed there like I was a trip on IR13 was also required, no difficulty whatsoever with using an advance (or whatever SBB’s equivalent is) for the Railjet on the IR13 to get to Sargans from Buchs.
It struck me how well prepared they were for this disruption and how quickly they were able to implement an unplanned diversion. The chances of the main Zürich to Sargans line becoming blocked whilst an Eastbound Railjet is between Zürich HB and Zürich Wiedikon (as opposed to before it departs Zürich HB) are very low and yet SBB were still fully prepared for that scenario when it happened. A UK equivalent would be a service leaving New Street but only making it as far as Smethwick before the line became blocked at Sandwell, then almost immediately reversing, going back through New Street and going via Aston and Tame Bridge Parkway to reach Wolverhampton instead, it likely wouldn’t happen.
So yes, Swiss railways are reliable. And on the rare occasions things go wrong they appear to be very good at handling it.
I this is a good example to mention a key tool in the reliability toolbox of the signalling and control staff - pre-planned contingency strategies. Since the whole railway network runs in a Takt, the timetable follows a standard hourly pattern, meaning it is feasible to pre-plan for almost any possible kind of disruption and develop strategies for each one, taking pathing constraints, diversion routes, and various other things into account. Obviously not every possible scenario will be covered, but mainlines (such as the line from Zürich to Sargans) being blocked and fatalities (yes, they happen in Switzerland too, with unfortunate frequency) are standard disruption scenarios, and the diversion via Winterthur and St. Margrethen is a typical measure that is taken in the situation described above. Those strategies may also include which lines to cancel and which lines should receive additional scheduled stops (e.g. most kinds of disruption to the line between Zurich and Bern will almost invariably lead to the IC1 and IC8 services making unscheduled stops in Olten to pick up disrupted connecting passengers).
As another example, the chronic unreliability of the inbound EC trains from Munich meant at some point SBB had a full-on strategy with different diversion routes and overtaking locations depending on exactly how many minutes late the EC train was arriving at St. Margrethen, in order to decide whether to make the IR13 scheduled to depart towards Zurich a few minutes after the EC should wait or not, which included pathing calculations about whether the late EC would subsequently get stuck behind an S-Bahn train in the Zurich area and by when exactly the IR13 would be able to catch up to its timetable should it depart late.
This means that instead of trying to make up these control strategies on the fly, they can take one of the existing strategies and apply it to the situation at hand, freeing their mental capacity to get the details right, because the big picture is already there.
Another key difference to the UK is the considerable flexibility the controllers have in dispatching spare or replacement trains to cover for delayed trains. There are agreements and contracts in place between almost all operators in Switzerland allowing last-minute allocations if a train happens to be in the right place at the right time during disruption. For example, there are numerous cases of a late ICE (nominally operated by SBB within Switzerland) from Basel being covered for by an SOB Traverso. If a driver and train are available, then they will be used to stabilise the service, and the contractual sorting out will happen afterwards if needed.