If the watch type is a "HTTP", is the page cached after the first download, skewing response times?
However, this can be undermined in one of two ways:
If you are on a corporate network or ISP that uses caching software such as a proxy server. If you repeatedly run a watch on an item in succession, the path to your site will already be "known" to your computer or your ISP, effectively caching the route to your server. In most cases, it is sufficient to download a page from a server in one minute intervals, which will avoid any caching problems. After a watch item is run over a period of one week, you should notice trends in slow response time.
To ensure that your network is not caching output, create a Watch Item for the URL http://www.lagado.com/tools/cache-test. When the Watch Item first runs, note the "page serial number", then run the Watch Item again. If the number changes, then WebWatchBot's results are NOT cached. If the number does not change, then the results are being cached.