More often than not, these IP68 enclosures do what they say on the box, It's the installation methods that fail these enclosures. ...can't tell you how many times on inspection i've found supplied fixing screw sealing caps absent, lids and doors not securely fastened, cable/conduit entries without sealing rings fitted, the list goes on and on. ..lol!!!
All these bits of kit have been type tested, many times by the various testing institutions, and wold not get the IP68 rating if they ever failed in these tests.
Having said that, It's always a good idea to apply a smear of vaseline or similar, to any exposed rubber type gasketing, whenever it has been disturbed by lid or door opening.