I have used pet insurance in the past and never had an issue claiming but for 2 dogs it is now quite pricey and we have sufficient savings to cover pretty much any eventuality so we do not bother anymore.
We do pay £12 p/m-ish per dog for the flea, wormer, health check and annual booster plan though as that does work out to be quite cost effective.
To answer your question though you have policies with lifetime limits for conditions or just renewable policies with a monetary amount per condition. Both have pros and cons. The lifetime limit looks good and means a condition continues to be cover for an amount of time but can run out quickly. The set amount per condition can be better however come renewal they will be sure to exclude that condition going forward so if it reoccurs you’re buggered.
As the dog gets older – particularly above 8yo but starting at 5yo- the premiums will ramp up significantly and the excluded conditions list tends to grow.