Is it beneficial to give trial access to the paid newsletter?

The situation that happened:

I see how some creators on Subtsack are monetizing their content (they have a section for subscribers who can pay to access articles, videos, and private chat).

My newsletter is free for the first two weeks. People who sign up receive it via email, and during this period, it is also freely available on the platform for everyone. After two weeks, access is closed publicly.

I tried to apply a weekly trial so that people could unlock articles from the archive and after the trial period has expired, they become paying subscribers.

However, this turned out to be ineffective, because a person opens the article they need, reads it, cancels the subscription, and then leaves. In this case, the 7-day free trial did not work for me. That is why I cancelled the 7-day trial and people are charged outright.

How do you approach subscription strategies regarding content (ideally a newsletter)?

It's not a tool, so I assume we need to approach these things differently.