The controllability of a flat is definitely dependent on the bike and type of tire involved. I had one once on a bike with stiff sidewalled, low-profile sport tires where I picked up a nail in my rear tire in the morning and then at the end of the day noticed that the tread on the tire had evaporated and the tire was toast. All that day I was riding quickly through twisty roads and hitting high speeds on long, empty stretches of central Idaho highway. I never suspected I had a flat the whole time.
Now, I check tire pressures a bit more often. A TPMS wouldn't be a terrible investment, though. I was already pretty good about checking tire pressures, and had checked my pressures that morning before starting the ride. A TPMS would have let me know and I would have been able to patch the hole and not have had to buy a new tire so soon.