Cache performance

Are there any conditions for the cache to work?
Even the same Jpeg file may or may not be cached on the CloudFlare side.
Below is the Apache access log inside the origin server.
This is the result of accessing the exact same jpeg file from different terminals.
The user who requested https
Instead of looking at the images cached on the CloudFlare side, we are looking at the images on the origin server side.
The cache is enabled and a list of cached items is output, but the following files are not displayed in it.
It has been viewed only 3 times. For example, is there a condition that the cache will be enabled if the number of accesses increases?

xxx.xxx.xxx.xxx - - [08/Sep/2021:13:22:20 +0900] “GET /05.jpg HTTP/1.1” 200 220110
xxx.xxx.xxx.xxx - - [08/Sep/2021:13:25:48 +0900] “GET /05.jpg HTTP/1.1” 200 220110
xxx.xxx.xxx.xxx - - [08/Sep/2021:13:26:15 +0900] “GET /05.jpg HTTP/1.1” 200 220110

May I ask have you enabled Edge Cache TTL, if so, what value have you set for it this option? Moreover, how about the Browser Cache TTL value (there could be some others too like last modified, expires, e-tag, cache-control etc. - maybe your host origin sends the “no-cache” value and Cloudflare respects it “as-it”)?

Furthermore, what kind of Cache Level are you using at Cloudfalre for your domain?

Following navigation for https://dash.cloudflare.com/?to=/:account/:zone/caching → Caching.

Do you have any custom Page Rules active?

It is valid from the beginning. I would like a server cache instead of a browser cache.

Also, today, I received an email that I was pleased with.
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平素より大変お世話になっております。
この度、御社を担当させていただくことになりました李と申します。
弊社のサービスをご利用いただいだき誠にありがとうございます。

最近御社のアカウントを検討した結果、DNSしか設定されていないことが確認されました。
御社の実務に対してSecurityとPerformanceも大切であれば、
ご提供できる機能もご紹介させていただきます。

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2021年9月9日(木) 1:08 fritexvz via Cloudflare Community <[email protected]>: