I tend to use the expression "more often than not" quite often in English, so naturally when I came across сплошь да рядом, I immediately adopted it and started using it. But I never hear other Russians use it, so I wonder if it's more of a literary expression and not commonly used in conversation. Is it better to use очень часто in conversation?
It is also important to mention that the expression "сплошь да рядом" or "сплошь и рядом" often has a negative meaning, when the person speaking criticizes the situation that ofter happens:
Он сплошь да рядом ошибается.
He makes mistakes very often (which is really bad in the opinion of the person speaking).
"сплошь да рядом" is a perfectly normal expression, but it has more common variants like "постоянно", "часто", "зачастую" (colloquial for "often"). In the majority of cases people prefer the most ordinary "часто". I bet that most English-speaking people prefer "often" or "frequently" to "more often than not".
There is a context where "сплошь да рядом" is most commonly seen. It is when you speak about some particularity that is common in people, things, in the way life goes. For example:
Люди сплошь да рядом судят о других по себе.
People more often than not judge others by themselves.
It may sound weird when you are talking about one particular object or person. The following sentence sounds artificial:
???Он сплошь да рядом забывает дни рождения.
He often forgets birthdays.
Он часто (постоянно, зачастую) забывает дни рождения.
I think "сплошь да рядом" is colloquial expression, I would expect to see it in journalistic genre or in informal conversation, but not in some official document or scientific article. "Очень часто" has neutral stylistic and can be used everywhere.
You can find plenty of good examples here: Russian National Corpus . It differs from just searching the word in Google, because Russian National Corpus is based on well-reputed sources, like classical books and a selection of magazines. There is also a separate subcorpus of spoken langauage.