Ultimately it will be as noisy as the RSS feeds the community is configured for. Most of the noise in local right now is from me adding new communities and new feeds as the bot is backfilling links already in the RSS feeds.
The bot currently checks the RSS feeds every 5 minutes (to capture breaking news quickly), but it only posts new links that it hasn't seen before. As we start to scale out I may change that to use some actual logic configurable per feed with rate limiting just in case we start to run into performance issues.