How is Tadir determined when either one can be considered more common?

Question

There is a principle called “Tadir v’she’eino tadir, Tadir kodem” - when presented with something commonly done and something less commonly done, the one that’s done more common takes precedence (Zevachim 89a et. al.).

What determines what is more common? For instance, on Rosh Chodesh Elul, do we say Barchi Nafshi before L’Dovid, since we say Barchi Nafshi during at least 11 months of the year, but we only say L’Dovid during 2? Or do we say L’Dovid first, since Barchi Nafshi is said on at most 20 days of the year, but L’Dovid is said on 51 days; alternatively, Barchi Nafshi is said at the conclusion of at most 20 tefillos, but L’Dovid is said at that of 102? In other words, if item A is more common than item B if you look at it one way, but item B is more common than item A if you look at it a different way, do we consider either one to take precedence, and if so, how to we determine which one?

Answer 1

There is a similar instance in bentching.

Shulchan Aruch in 188:5 states that Retzei comes before Yaaleh Veyovo on a Shabbos that falls on Rosh Chodesh or Yom Tov. The Mishna Berura (13) says that it's because Shabbos is Tadir.

Now, if you count the amount of times you say Yaaleh Veyovo including in Shemona Esrei it's more than the amount of times that we say Retzei. However, the Mishna Berura uses the word "Shabbos" not "Retzei" seemingly to avoid this problem. It sounds like he means to say that it's not based on the amount of times you say the tefilla but rather the day that causes the tefilla to be said is Tadir (in this case Shabbos vs. Yomim Tovim and Rosh Chodesh).

In fact, in your case of L'Dovid and Barchi Nafshi, the Mishna Berura in 583:2 clearly says that you should say Barchi Nafshi first. The Maateh Ephraim (583:6) says the reason is because it is Tadir since it is said every Rosh Chodesh while L'Dovid isn't said every Rosh Chodesh. R' Yackov Kamenetzky (Emes L'Yackov 1) explains that although L'Dovid is actually said more times than Barchi Nafshi, since it's not because of a day rather just a season, it doesn't become Tadir just by being said more times. Barchi Nafshi is because of the day.

So just like Yaaleh Veyovo vs Retzei, we always look at the amount of days that cause something to be said or done, not the actual amount of times it is done.

P.S. my calculation for more Yasleh Veyovo is as follows: Rosh Chodesh 54 Tefillos 10 meals (4 on Rosh Hashanah and at least 2 shabbos Rosh chodesh per year) Yom Kippur 4 Succos 24 Tefillos 17 meals Pesach 24 tefillos 17 meals Shavuos 6 tefillos 4 meals Total 160 Retzei is 50 times 3 which is 150 Obviously in Eretz Yisroel it's equal, but if someone washes on Rosh Chodesh during the week that would add more Yaaleh Veyovo.

Answer 2

This question is similar to the question of lighting Channukah candles on Motzaei Shabbos Channukah. There are different minhagim. Look at the footnotes here, where some poskim hold that havdallah is tadir even though in the micro-time period Channukah is more tadir. This however isn't an exact comparison.

You should also know that some things take precedence over tadir v'ayno tadir e.g. something that is pertaining to a special time period, like the special Yom Tov tefillos before krias HaTorah coming before Brich Shmei even though the latter is tadir. Seeing as how L'Dovid isn't directly due to a special time and the Shir Shel Yom of Rosh Chodesh is due to the special Shir of Rosh Chodesh, that is another reason why it might come first.