It is well worth it for everyone who hasn’t done so to check the website to see what they will get. I have been paying voluntary contributions to cover my COPE amount (the contributions for the years I was contracted out), and if I continue to do so I will get the full state pension. If I hadn’t realised there was a shortfall (even after 44 years of full contributions) I would have got a lot less.
It is a minefield- any periods of non-contributions (eg maternity, gaps in employment, term-time contracts and so on) can result in contributions not being counted, as only ‘full years’ add to your contributions. Those who got NI paid because they were bringing up children or in benefits can end up with more full years than those who worked for decades - it is not straightforward, so do check your own record and assume nothing. You can question anything that doesn’t tally with your own records, but it is better to do this ahead of time, as if can take a while to get answers.
If you are planning on retiring before you are 66, do so in April, to get another full year, as retiring in February will mean that you have made 10 or 11 payments that don’t get counted. Speak to the government pensions advice service, or get private financial advice if you haven’t already done so and are over 55. The earlier you know your position, the easier it will be to plug any gaps.