If you've had three in the last couple of days, have a good check of your tyres to make sure it isn't the same thing causing the puncture all the time.
I suffered quite a few in succession last year and I found the tape that covers the wheel underneath the inner tube had moved position. I kept getting punctures on the inside of the tube that baffled me for quite some time. When I sorted the problem and ensured the tyres were fully inflated I haven't had one for a while. <Quickly touches wood>
Two thorns on one ride sounds like you just went through too many thorns!
If you find you're 'always' getting punctures then it could be what Steve H says. Or it could be that you ride where the spiky stuff is. Off-road it'll be hawthorn trees, on-road you're probably riding in the gutter where all the glass and nails end up.
I usually bin a tube after 3 repairs but what's to lose?
You can get these armoured tyres, and you can also get 'slime' tubes that have green gunk in that fixes the puncture without you knowing that you even had one. However, all that does increase weight a little bit, which can make the bike feel slightly less responsive, but is probably better than getting a puncture though. I've (touch wood) had very little trouble with punctures over the years and now just use normal tyres and tubes with the correct pressure in. And I carry a spare tube just because Sod's Law says if I don't I'll get a flat.
I don't really have a limit on the number of repairs, mainly because I can't count that high. If a tube gets a slow leak, or can't be easily patched, then I'll bin it because replacements only cost a couple of quid, but I'll mostly keep repairing whilst I can.
Got to admit i stick a new tube in then patch the old one as a spare ,inner tubes are that cheap and running good tyres (touch wood) mean i hardly get them.
The tyre that's in will last until next time then the patched spare goes in as the "new " one.So a couple of patches is the most mine haveon.