Our Free XML Sitemap Generator isn't helping with crawl budget optimization, what are we missing?

hey everyone, hope you're all doing well. we recently rolled out our 'Free XML Sitemap Generator' and while its getting some good traction, we're scratching our heads a bit over some unexpected results. the main issue is that the sitemaps it generates don't seem to be doing what we really hoped for in terms of influencing search engine crawl budget or really speeding up the indexing of new pages on our users' sites. it feels like a core piece of technical SEO is just not clicking into place for us. we've gone through a bunch of troubleshooting steps already, like double-checking that the sitemap format is strictly compliant with all of Google's guidelines, even down to the character encoding. we also ran extensive checks for any broken links or pesky redirects hiding within the sitemaps our tool generates, thinking maybe that was confusing crawlers. of course, we verified that robots.txt isn't accidentally blocking the sitemap itself or any of the important pages it references. and yes, we've made sure to implement `lastmod` and `changefreq` tags correctly, thinking that might give crawlers a better hint. so now we're turning to the community for some practical advice. are there any advanced XML sitemap generation techniques or perhaps some more nuanced strategies for better crawl budget management that we might be completely overlooking? also, since it's a *free* sitemap tool, are there common pitfalls or limitations specific to such tools that could be hindering their overall SEO impact, maybe something to do with how they're submitted or updated? finally, beyond just looking at the raw number of 'indexed pages', what other metrics or indicators should we really be focusing on to accurately measure the true effectiveness of our sitemaps and their impact on a site's visibility? we're really keen to get this right and provide a truly valuable tool, so any practical tips or insights from you experienced folks would be super helpful. thanks in advance for your time!