Transients labelled ‘Does not expire’

It depends on what the transient is from. Most transients are designed to be temporary data and so are safe to remove, but it’s certainly possible for a plugin to add a transient that needs to remain in the system.

Thanks. OK I need to be careful!

Another way to ask the same question is: do non-expiring transients matter much?

Thanks again for quick reply.

That entirely depends on the source of the transients.

Transients are used for a lot of different purposes and it is not possible for me (or anyone else) to accurate say how important a particular transient is without knowing exactly what the transient is used for.