i think this is because Dokja has read all 1800+ regressions on Yoo Jonghuk. In all these countless and repetitive regressions, Dokja would’ve gotten information on what items to get or how to defeat certain enemies from Yoo Jonghuk’s experience and finds after countless regressions. It’s not clarified, but it’s hinted that each time Yoo Jonghuk died in Ways of Survival, the novel will go back to the first scenario and describe changes he made each time he regressed. The novel should be extremely detailed, which explains why Dokja knows almost every item and enemy attack patterns, that’s why the novel had over 3000+ chapters and it took Dokja 10(?) years to read all of it.