Need to specify session timeout as a setting value?

I was login as admin when I put some product information. When I was ready to click the submit button, suddenly I was called by someone and talked on the phone for about 30 minutes. After finished talking, I continued my admin work, and press the submit button. But unfortunately the session has timed out, and the login screen show-up, before it could save the information to the database.

Then I tried to press the 'back' button of my browser to retrieve the product information I previously entered to the screen. But unfortunately there was no way I could get there because the login screen always blocked me from there.

After I look into the source code, it looks to me that it utilizes the default session timeout in php.ini, which is set up for 24 minutes.

I think it is handy if we can specify the session time out as a configuration value somewhere so we can use bigger value if desired (well I'll choose 24 hours for my session timeout)