Is JR pass worth it for my trip?

I'm traveling by train to the following cities over a 21 day period starting Oct 31-Nov 20, 2024. Our trip is longer but these are the days I would use the Rail Pass. Is the pas worht it for this time frame and destinations?
Tokyo to Mashiko, Mashiko to Matsumoto, Matsumoto to Nakatsugawa, Natatsugawa to Nagoya, Nagoya to Toba, Toba to Kyoto, Kyoto to Takamatsu, Takamatsu to Kurashiki, Kurashiki to Hiroshima, Hiroshima to Yamaguchi, Yamaguchi to Hagi, Hagi to Fukuoka.

Since the extreme price increase last year, the Japan Rail Pass almost never pays off. Your journey is no exception. Even a 14-day pass would be more expensive than individual tickets. However, buying tickets for so many different journeys in a foreign country can be dauting for some people, and the cost of the 21-day pass may still not seem too steep to some people.

In other words: those who want to save money should stay away from the Japan Rail Pass. Those who don't mind to pay extra for convenience, go ahead and use the pass.

Note that even in terms of convenience the Japan Rail Pass does come with some minor (?) downsides. Most prominently: pass holders can't use the fastest train categories along the Tokaido/Sanyo Shinkansen.

Good answer, I think, and not the usual one you hear these days. Many travelers are able and willing to pay extra for better seats on an airplane, larger rooms in hotels, cabs instead of buses to get around in Kyoto, and so on. But when it comes to rail passes, all I ever seem to hear since the price increase is that people should not buy a JR pass because it "doesn't pay off" for their itinerary. Of course there are limits to how much anyone would want to pay for the convenience of the JR pass (coupled with the inconvenience of not being able to use the Nozomi and Mizuho, and the other downsides, which bother some people more than others). But Uji makes a good point.

A rail pass calculator can give some sense of whether a pass will "pay off" for a given itinerary, or you can use a route planner such as Navitime to obtain ticket prices and just add up the segments. (Just don't look at the price you pay if you actually make reservations through Navitime!)
https://www.japan-guide.com/railpass/

I guess I am one of the few travelers who can still save money using a nationwide JR pass, but in some cases I would be willing to pay extra for the convenience and flexibility of being able to make as many reservations as I want, online, and to change those reservations as many times as I want. I used the JR pass online reservation system extensively on a trip earlier this year, with a 21-day nationwide pass, and found the system to be extremely easy to use, and flawless in operation. And the ability to make reservations (and pick seats) 30 days in advance was a godsend.

I only wish that JR West's regional passes were so convenient and easy to use. There is no question that they are a better value in terms of cost, and the ability to use the Nozomi and Mizuho is a plus, but there are so many conditions and restrictions around reservations, ticketing, and receiving the pass. I would be willing to pay a little more for those passes to have all that stuff go away and have them work like the nationwide pass. Unfortunately, not an option.

I didn't run the numbers, but you didn't say anything about returning back to Tokyo. If just going one way, I don't see how you can make it pay off with an itinerary like yours. To at least break even, you'd need to be doing a lot of travel by bullet train, and since the pass is 100,000 yen, I don't see your fares totaling anything close to that. Depending on where you are spending those 21 days, a regional pass might pay off though -- you'd need to check.
BTW, while under the old prices you couldn't ride any Nozomi or Mizuho trains with the pass, with the current pass you can, although there is a stiff surcharge you'll have to pay for doing so - making the pass even less of a good idea.

Of course it depends on your itinerary and I found some legs you cant or should better not use JR.

Mashiko: you can’t get there only by JR trains.

Nara to Toba to Kyoto: Kintetsu is faster, comfortable and convenient.

You may consider Kintetsu Rail pass 5 days, 4500 yen.

https://www.kintetsu.co.jp/foreign/english/ticket/krp_5day.html

For Limited Express trains you must buy their tickets separately though.

https://x.gd/7KNka

From Kyoto to Hakata, JR West’s Sanyo-San’in Area pass 7 days, 23000 yen might work well.

https://www.westjr.co.jp/global/en/ticket/pass/sanyo_sanin/

If you use this pass note that you can’t take Shinkansen from Kyoto to Shin-Osaka so you will need to take Rapid service or Limited Express train from Kyoto to Shin-Osaka and then transfer to Shinkansen going west.

If you buy nation-wide Japan Rail pass, you can’t travel stress-free. There are some leg you can’t (or should not) use JR.

Nara to Toba to Kyoto: Kintetsu is faster, comfortable and convenient.

Sorry, not Nara but Nagoya.

I didn't run the numbers (because a 21-day pass would be so expensive for that trip), but would observe the initial piece (Tokyo to Mashiko, Mashiko to Matsumoto, Matsumoto to Nakatsugawa, Natatsugawa to Nagoya) looks like lots of slow travel on inexpensive trains (non-shinkansen), therefore your more extensive travels from Nagoya onward might favour a regional pass.
Also, as mentioned, non-JR trains can be more useful for things like getting to/from Toba.