I’ve been thinking on new feature with solved plugin. 
Now, when you edit a category, have the option to “auto-close” topics by time… that’s ok.
If, for example we set 3 month for auto-close topics, we would need to reduce that timing if the topic is solved. So, right now a mod, or someone for staff (or TL4) are seeking solved topics to reduce the auto-close time manually, from 2190 hours to 168 hours (1 week; seven days).
Why that change? Well, when a user open a support topic and solved it, sometimes other interlocutors want to say what they think, so a grace period of 7 days is left for everyone to respond, and if no one answers, it closes automatically.
What do you think?