I don't fly nearly as much but here's my take:

The number of IR(R)OPS wouldn't directly depend on the distance travelled but rather on the number of segments flown.

In fact, people who clock up a lot of miles can be very unlikely to experience delays if they primarily do long-haul, where schedules allow more leeway, so the flight can leave delayed and still arrive ahead of time, which also makes subsequent flights less prone to disruptions stacking up. Further, airlines try to make sure those flights are the last to be affected.

For a given number of miles, you're much more likely to suffer delays flying short-haul then, and it's not as much about luck as whether you fly:

• to or from a busy airport (not necessarily related to size but tight intervals between flight operations, think LHR)
• in the late afternoon or in the evening (unless the airline operates their equipment without a break for the night, they are less likely to start the day with a delay)
• on carriers that maximize aircraft utilization, particularly operating away from their base (a single technical issue affects many flights and no replacement aircraft immediately available)
• into areas that experience seasonal severe weather patterns as opposed to where the weather is more or less stable throughout the year (think ORD vs ATL)

Finally, some airlines have the propensity to go on strike while on other carriers it's virtually impossible as the perpetrators would quickly be lined up, executed, and fed to the pigs (well, not sure about that last part).