SIGMA-detection-rules VS Graylog_3.0_Content_Pack_Active_Directory_Auditing

I am currently employed as a cyber analyst, and we've recently implemented an Endpoint Detection and Response (EDR) system. Upon closer inspection, I've observed that numerous events are not being flagged as alerts. This raises a crucial question: should I take the initiative to create custom rules to ensure these events are brought to our attention, or should I rely solely on the EDR's intrinsic capabilities to detect and classify threats? As a potential solution, I'm contemplating the implementation of rules based on Sigma, such as those available at the following repository: here. Your insights and experiences on the effectiveness of this approach would be greatly appreciated. Thank you for your time and assistance.

Depending on whether this is up your alley either look for a MSSP/MDR/Managed BlaBla provider or head on to - https://github.com/splunk/security_content - https://www.elastic.co/guide/en/security/current/prebuilt-rules.html - https://github.com/mdecrevoisier/SIGMA-detection-rules - https://github.com/Azure/Azure-Sentinel to get an idea of what to look for. MITRE ATT&CK and the related DETT&CT should serve as an additional eye opener. Ah yes - forgot the bible on log management from Anton Chuvakin in the above list.

Then you can go about making dashboards for high level information around the logs you are collecting. They used to have awesome ones in their marketplace but have since removed them for some reason. Here is a reference to one of them https://github.com/aydnyldrm/Graylog_3.0_Content_Pack_Active_Directory_Auditing