Google is constantly testing this for usability/relevancy purposes - they want to show the visitor that the URL matches in someway their query.
So your answer is hidden in the examples you have shown (i.e. there is no one length).
Different URL constructs will be shown differently and truncated/edited to:
show that the URL filename matches the some/all/part of query (for highlighting)
removes redundant intermediary segments/folders (when not matching query)
show breadcrumbs in URL construct when page coded appropriately
It's an interesting observation you have made about cacheing being allowed or not, but since this is not standard practice, you'd be better served following the more common practice.
Remember that the URL is only shown for (searcher) validation purposes and will only have a (minimal) impact on Click Through Rates (CTR). Page title and description are more worthy of your time in this respect.
The final takeaway is that you should, where possible, make your URL and file-path as short and relevant as possible. How it's constructed (segmented/hyphenated etc) will all be handled appropriate to the search query.
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Google 不断出于可用性/相关性目的对此进行测试 - 他们希望向访问者展示该 URL 在某种程度上与他们的查询相匹配。
所以你的答案隐藏在你所展示的例子中（即没有一个长度）。
不同的 URL 结构将以不同的方式显示，并被截断/编辑为：
这是您对是否允许缓存所做的有趣观察，但由于这不是标准做法，因此遵循更常见的做法会更好。
请记住，显示 URL 仅用于（搜索者）验证目的，并且只会对点击率 (CTR) 产生（最小）影响。在这方面，页面标题和描述更值得您花时间。
最后的要点是，您应该尽可能使 URL 和文件路径尽可能短且相关。它的构造方式（分段/连字符等）都将根据搜索查询进行适当处理。
Google is constantly testing this for usability/relevancy purposes - they want to show the visitor that the URL matches in someway their query.
So your answer is hidden in the examples you have shown (i.e. there is no one length).
Different URL constructs will be shown differently and truncated/edited to:
It's an interesting observation you have made about cacheing being allowed or not, but since this is not standard practice, you'd be better served following the more common practice.
Remember that the URL is only shown for (searcher) validation purposes and will only have a (minimal) impact on Click Through Rates (CTR). Page title and description are more worthy of your time in this respect.
The final takeaway is that you should, where possible, make your URL and file-path as short and relevant as possible. How it's constructed (segmented/hyphenated etc) will all be handled appropriate to the search query.