Also continuing to thrust after ejaculation pushes the fluid down to the base ring, sure it's a good enough fit for pre-cum sex but it's not a perfect seal so combined with extra fluid and even small amount of deflation there's a risk of it running out.
Some men (and I would guess some women) aren't aware of the need to hold onto the condom during withdrawal. Another factor I've found associated with splits is what I call 'porn star' bouncing, exiting and reentering on each stroke drags the condom back. Similar with condoms being pulled tight over the glans (penis head) during application, as soon as I notice this I explain the loose teat is required to allow slack for thrusting and to hold the ejaculation.
All good points .. often ignored.
Sure I've contributed to another thread about this fairly recently, but the 98% is the top figure for contraception and assumes they are used correctly. Not used correctly can reduce that figure down to well below 90%.
You would like to think that all punters and SPs would know how to use them correctly but that has not been my experience as is highlighted by some of the comments in this thread.
Educate yourselves. Condoms don't have to rupture to fail.
(a) Avoid very cheap condoms
(b) Roll them on, avoid stretching them on especially with long or sharp nails.
(c) If you have a very small penis use a small/slim fit condom.
(d) Whatever size you are, if you are not fully erect ie stiff you must hold it in place whilst attempting penetration.
(e) Ensure plenty of lube (natural or artificial) especially with anal where of course there is no natural lubrication. Ensure condom friendly lube.
(f) Withdraw immediately once ejaculated and hold in place whilst doing so.
(g) Remember that the average time for penetrative sex is between five to ten minutes. If you are banging away for extended periods consider replacing the condom.
(h) Always swap condoms if alternating between vaginal and anal.
(i) Ideally if a condom has been used to give covered oral it should be changed for a fresh one before penetration ... but this rarely happens.
(j) Take control of the process. Many inexperienced wgs will not know how to use them as they either haven't used them in their personal lives or if they have the male will probably have applied them.
(k) Repeat point (e) above as needed. This is the biggest cause of condoms 'splitting'
Personally I have only had maybe four instances of condoms breaking in nearly 50 years of sexual activity correlating to less than 0.5%. Only two of those were with a wg, although they both happened with the same girl in the same session and probably fell under category (a) above
