I have a medium-sized website and an XML sitemap for it. Historically I have been using the XML-Sitemaps website to generate it.
I've been thinking that I would like to instead just manage the sitemap on my own, just editing and adding to it with a text editor. The difficulty I would have is related to keeping track of "lastmod" information. I frequently edit many pages very randomly. Keeping the lastmod information accurate on my own would be very difficult.
I realize you can leave the lastmod info out of the sitemap. My question would be, if I did leave out the lastmod info am I inviting a situation where GoogleBot (and others) would burn through a whole lot of my bandwidth because it would be unkowingly re-evaluating pages that hadn't been revised. Or possibly on a practical level this a non-issue? In general is "lastmod", "changefrequency", "priority" metadata all that important to include?