meandering topics

I like the ability to search topics. It is also nice to have different topic headings (horse evolution, transitional fossils, etc) but during the debate, I guess not surprisingly, the topics tend to 'meander' as debaters bring up side issues that need to responses. Other than having a moderator for each topic, I can't think of any way to avoid this. Perhaps, simply an occassional reminder among debaters would be a good idea or am I wrong and this doesn't really matter to anyone?