Understanding the Meaning of mpm prefork Settings

There is a description in Apache's Document.I will reply while quoting.

Apache MPM Common Directives

https://httpd.apache.org/docs/2.4/en/mod/mpm_common.html

From MaxRequestWorkers Directive:
For non-threaded servers (i.e., prefork), MaxRequestWorkers translates into the maximum number of child processes that will be launched to serve requests.

From ServerLimit Directive:
With the prefork MPM, use this direct only if you need to set MaxRequestWorkers higher than 256 (default).

MinSpareServers, MaxSpareServers are settings for the number of waiting servers, so it doesn't make sense in terms of whether the request can be processed.
If the process is insufficient, start the server up to the number of ServerLimit.
If you have a waiting process in place, you can respond immediately without starting the server when you receive a new request, so you should set it up for responsiveness.

MaxConnectionPerChild describes the configuration of a forked server that terminates when the number of connections reaches the configured number:"0" does not terminate no matter how many times you connect.
It seems that it is often set as a countermeasures against memory leaks.(In other words, it is often set in case there is a leak.)

From MaxConnectionsPerChildDirect:
The MaxConnectionsPerChild direct sets the limit on the number of connections that an individual child server process will handle. After MaxConnectionsPerChild connections, the child process will die.
If MaxConnectionsPerChild is 0, then the process will never expire.