Geoffers... with reference to your final sentence, I can change a wheel, no problem. I thought that most of my post was dedicated to those who'd have difficulty changing a wheel. Of course a call to a breakdown organisation may be their first or last resort. I also tried to help those who would change a wheel but who might need 'more power to the elbow' to loosen tight wheelnuts. This by suggesting a 'pipe extension' to the spanner - a sleeve slipped over its handle for much more leverage. Just 6 inches extra length to the handle makes a massive difference. Easy to DIY and store in the boot with the spanner.
Nor was I suggesting that it's OK to leave a nail in a tyre... indefinitely; I did clearly imply get it to a repairer.
However, I should have added the reason for not extracting the nail too soon. If you were to unwisely extract a nail before changing the wheel or getting it to a repairer, you will then most certainly have an emergency situation as the tyre will lose all air almost immediately. But you probably know that. I should have added I'd drive at significantly reduced speed with a nail in it till getting it to the repairer.
I've seen lots of road situations where it is downright hazardous to be changing a wheel. Raining, luggage out once, too. Yet people risk it partly, I suspect, because of the temptation of that spare in the boot. If it's a typical puncture - a nail/screw in the tread - they could use 'gunk' in that situation and duration of exposure to hazard is much reduced.
Spare or no spare? Or spare AND a can of gunk as an option depending on situation? This surely offers the best of both worlds. It's all arguable opinion anyway because everyone has different driving patterns and different perceptions of risk. In this case level of risk - actual and perceived - of getting a puncture.
Nevertheless, my previous post was intended to be helpful for those without a spare, for those with a spare, for those who cannot physically change a wheel and for those who can. Sorry, Geoffers, if it did not appear entirely helpful. I hope this helps.