I work as a network tech for a globally spanning ISP specializing in fiber services, handling major maintenances that are service effecting for business and government customers (SLAs are in effect). These maintenances are planned and tracked through various excel sheets - housed either in a shared network drive (so yeah, we may run into issues where multiple people are trying to edit the same doc at once), or excel tables in a SharePoint.

Prior to the merger of companies I recently went through, we had actual database systems to track this stuff that worked just fine. And now we're relying on the same shit a grad student would use to track their doctorate progress. It'll work until it doesn't. Looking forward to the shit-show if it gets me overtime.