[Pseudoscience-is-malarkey (OP)]

When I ask my friends, colleagues, etc, how often they have sex with their spouse/partner they typically say "twice a week." Should it be more than that or possibly less? One expert in an editorial for the New York Times in 1942 said that sex more than once a week is not good because too much of it makes one sex-obsessed and will eventually get bored with monogamy, driving at least one of them to seek sex "extramaritally".
Should we say f*** off to the experts and simply have sex when we feel need, as long as it's not in front of people, forced, during work hours, or while eating a tuna fish sandwich? Kind of like the debate over hydration health: "how much fluid should someone drink to prevent dehydration", where the sane answer is simply "drink when you're thirsty"?

"Our marriage counselor says that in order to save our marriage we should have sex every night. Great... now we'll never see each other!" - Rodney Dangerfield

[alancalverd]

more than one time a week is not good because too much of it makes it too boring, less special, and will drive at least one of the spouses to seek sex "extramaritally".

In other words, if you have so much that you are bored with it, you want more. For "expert" read "idiot". Par for the course anyway - I've never met a psychiatrist or counsellor that I would consider normal or who had a happy marriage.   

There are two correct answers to the question

1. As often as we like, in ways and places beyond your wildest imagination, and we re-plaster the ceiling twice a year.

2. None of your business.

[Pseudoscience-is-malarkey (OP)]

We re-plaster the ceiling twice a year.

Wow... you must have an enormous penis.

[Pseudoscience-is-malarkey (OP)]

Or something.

[alancalverd]

There have been no complaints. But I get a smoother finish with a conventional ladder and trowel. 

[Colin2B]

...... or while eating a tuna fish sandwich?

Hey, if you’ve never tried it don’t knock it 

[Bored chemist]

I did hear that the answer to the OP's question is that it's age dependent.

It goes from tri-weekly to Try weekly to try weakly.

Should we say f*** off to the experts and simply have sex when we feel need,

Yes.
(or, arguably "no", because in this context , you are the experts)

[alancalverd]

There's a difference between the question "how often do you?" and the so-called expert opinion on "how often should you?".

Nobody will give you an honest answer to the first question, and nobody knows the answer to the second. The Bayesian asssumption is therefore that they are all lying.

[Pseudoscience-is-malarkey (OP)]

There have been no complaints. But I get a smoother finish with a conventional ladder and trowel. 

I don't want to shake your hand, I want to shake your penis, and possibly get its autograph.

[alancalverd]

Mother warned me about such offers, but the night is young.