Being replaced with known brand items or genuine Jaguar parts? I've used lesser known lambda sensors/Chinese made items which didn't last on various cars.

 

Yep

 

The oxygen sensors on your car are covered by an extended 15 year warranty, see here: Oxygen Sensor Help!!! - Jaguar Forums - Jaguar Enthusiasts Forum
Contact your nearest JLR dealership and get them replaced free of charge.
If you have already done this I would assume the replacements were factory OEM in which case I have no idea why they are continually failing.

 

Ah yes, OP is based in the USA, not UK. I forgot in the US they had a 15 year lambda sensor extended warranty, which of course doesn't apply to the UK.

 

Thanks for the information about the 15 year warranty. I did not know that, but apparently my service writer does know. All replacements done by Jag, I assume with Jag parts.
Waiting until they get a loaner car for me, for replacement #7.
Thanks again.
Don