There is no correct number
Nothing in tarot's structure sets a frequency, and readers who work daily and readers who work monthly both produce good readings. What varies is what each rhythm is good for, and the honest answer to how often you should read is that it depends on which of two failure modes you are closer to.
That framing is more useful than a number, because the failure modes are recognisable from inside and a number is not.
The failure mode at the frequent end
Reading too often turns the deck into a way of not deciding. The pattern is recognisable: a question asked on Monday, asked again on Wednesday because Monday's answer was uncomfortable, and again on Friday with slightly different wording. Nothing is being learned; a decision is being deferred while looking productive.
The tell is not the number of readings but whether they are about the same thing. Three readings a week on three different questions is a practice. Three readings a week on one question is negotiation.
The failure mode at the infrequent end
Reading rarely means you only reach for the deck in a crisis, which is the worst possible condition for reading. You arrive with the outcome you need, no recent practice, and enough distress to make every card mean what you are afraid of. Readers who only read when something is wrong reliably report that tarot feels ominous, and the frequency is why.
It also means you never build the corpus that makes tarot useful over time. Patterns only become visible across a record, and a record of four readings a year has nothing in it to see.
A structure that avoids both
The rhythm most experienced readers converge on has two tiers. A daily single card, kept to thirty seconds, which is a check-in rather than a reading. This is what keeps you in practice and builds the record. Then a proper spread when there is genuinely something to look at, which for most people is somewhere between fortnightly and monthly.
The two tiers do different jobs. The daily card keeps the deck ordinary, which is exactly what stops crisis readings from feeling like verdicts. The occasional full spread is where the actual thinking happens.
The test
Look back at your last ten readings and count how many produced something you did. Not something you felt or found interesting: something that changed what you did next. If the number is low, your frequency is not the variable that needs adjusting; the questions are.
If the number is reasonable and you still feel you are reading too much, you probably are not. The people who read too often are not usually worried about it.
What changes at each rhythm
Daily reading makes the deck ordinary, which is its main benefit and is easy to undervalue. A reader who pulls a card every morning has drawn The Tower a dozen times in unremarkable circumstances, and it has stopped being frightening. The same card arriving in someone's third reading of the year lands like a verdict, because they have no context for it.
Weekly or fortnightly reading is where most of the actual thinking happens, because enough has changed between readings for a question to be genuinely different. Monthly reading suits people using tarot for review rather than decisions, looking back at a period rather than into a situation. All three are legitimate, and the mistake is expecting one rhythm to do another's job.
Frequency for readings you give other people
Reading for others has a different constraint: attention rather than the deck. Most readers find that quality drops noticeably after two or three readings in a sitting, because the delivery (hearing the question properly, choosing what to say, watching how it lands) is more demanding than the interpretation and it does not survive fatigue.
If people ask you to read regularly, a fixed number per session is worth setting in advance. It is much easier to say "I do two" at the start than to stop after the fourth when you have already lost the thread.