GSC Crawl Stats Report

Hello, We currently have a website. We are WordPress Theme Developer and place themes in our website. I have one question about Crawl Stats in GSC. Should it be constant? I have seen people say it should be somehow constant graph only some up spikes. We have subdomains for live preview of themes also. Can I no index them? I have shared my crawl report below. Are these numbers okay? Also few pages mea are taking weeks to be updated.