And what prevents/dissuades you from putting another one out?
Well they last 5mins (10 if crafted)
So you don't want to put another one out until the old one is used up else waste.
So once the old is used up you sitting fighting in darkness (if you even happen to be near it still), but likely have a mob pulled back to it or can't find where your location is because it's dark again.
I think the charge up would be one option, but really 5mins is just very short. You likely have the numbers, but I would be that very very small % of people even use ground torches at all. Ask yourself why? I would say the lighting radius + duration, are the major factors, along with likely roaming looking for whatever they looking for.
Is there a reason 5mins (10 for crafted) is a good starting point for you? Is there something we missing? Do we need to lower the drop rate and increase the cost to make it better what's the issue? Server lag? Afraid people are going to spam ground torches everywhere?
What are the negatives we looking at so maybe we can help see it from another angle or even help give information on how we disagree/agree with those reason(s).