I don't think there's a tweak for that but you can edit a plist file to change the values.
Using iFile, navigate to /Applications/Preferences.app/General.plist. Open General.plist as a text viewer. Scroll down & look for the lines below.
<array>
<string>1_MINUTES</string>
<string>2_MINUTES</string>
<string>3_MINUTES</string>
<string>4_MINUTES</string>
<string>5_MINUTES</string>
<string>NEVER</string>
</array>
<key>validValues</key>
<array>
<integer>60</integer>
<integer>120</integer>
<integer>180</integer>
<integer>240</integer>
<integer>300</integer>
<integer>-1</integer>
Tap Edit. Change the value to your liking, I'll set it to 30 seconds as an example. See below.
<array>
<string>1_MINUTES</string>
<string>2_MINUTES</string>
<string>3_MINUTES</string>
<string>4_MINUTES</string>
<string>5_MINUTES</string>
<string>NEVER</string>
</array>
<key>validValues</key>
<array>
<integer>30</integer>
<integer>120</integer>
<integer>180</integer>
<integer>240</integer>
<integer>300</integer>
<integer>-1</integer>
Tap Save. Reboot your device.
Note: This works for me but it doesn't guarantee that it will work for you. This may cause problem to your device & at worst will force you to restore. Try this at your own risk.