How often do issues arise in the coughpit? Do you have any flights where there are no issues? What's the most common issue you deal with?
Most issues are external to the coughpit. Passenger issues, ranging from simply disappearing in the terminal right through to medical. Most are handled readily enough, but can be time consuming. For instance a passenger who needs to be offloaded will cause about 15 minutes delay. That could cost you your slot, or perhaps cause you to end up at a lower level. That in turn burns more fuel, and might cause issues later.
Weather would be the most pervasive issue, but it is, of course, just part of the job. A four sector flight from Oz to London, could give you the entire range of snow and ice to tropical thunderstorms. Again, part of the deal.
Aircraft MELs, which are basically acceptable defects exist on almost all flights. Most are trivia, and have no effect on the coughpit or cabin. But some can require quite time consuming procedures, and these are overlaid onto the normal procedures, and serve to add to the time pressures. At the very least, you need to read through each and every one of them to ensure you understand their ramifications.
ECAMs are the procedures associated with the automatic warning systems. The system detects a fault, sets off the master caution, and brings up a procedure for you to follow. Airborne, you generally resolve the situation, and as long as it doesn't require a landing as part of the procedure, you can continue the flight. But on the ground, you need to complete the ECAM, and then go into the MELs to determine whether you can continue the flight or have to go back to the gate.
Many ECAMS consist of nothing more than 'crew awareness'. In that case the system has detected the fault, automatically done what it can about it, and is telling you just to keep you in the loop. Nevertheless, that could also reference an MEL, and that will need to be consulted.
A recent ECAM came up during engine start. Obviously at that point our attention is on the engines, but many other systems are coming to life, or having power or air sources changed during that period. The ECAM was somewhat cryptic, IFE BAY VENT VALVE FAULT. The procedure said simply IFEC - OFF (which is one of those switches that you never touch and need a search to find). It added that the IFE may be available in flight. The MEL said that IFE would have to be left off if the 'in flight' component was missing. So, now we have two engines running. We may have to go back to the gate, as IFE is currently off throughout the aircraft, but, we may be able to recover it in flight. Cabin crew use the IFE for safety briefings, so they need to revert to manual briefing. After a bit of discussion, we decide to go. The normal start procedures have been interrupted, so we need to complete them, and then back up a bit to ensure that nothing has been missed. Get airborne. Call engineering and get them to have a good look at the system. We know that leaving it off is safe, but it's a long flight without IFE, so we want them to ensure there's no risk to turning it back on. Eventually reactivate the system, and it behaves as advertised.
Most flights have zero ECAMS or faults. Most that do come up are quite trivial. I'm touching wood as I say this, but it's some years since I've had a significant ECAM, and even then it didn't stop us getting to destination. The biggest issue with anything is always time. It's very easy to lose time whilst sorting out procedures, especially when they've been translated from French, via Polish, Latin, and Greek. Hasten slowly is always the best way to move forward, but you need to balance that with the fact that an aircraft is moving at about 1,000 feet per second, you you never want it to get someplace that your head didn't get to a couple of minutes previously.
To directly answer your question though...most flights have no issues. And even if they do, it's my job to make them go away.