I can guarantee the following happened:
- your employees made more mistakes during weekend work
- at least a few had deteriorated health / sleep
- your teams morale took a hit
- you accomplished less than you would of had you had your employees come in regular weekly hours
Required weekend work is always a fault of management to properly plan and execute. Always. The few times I had my teams work the weekend I always admitted how I was at fault and how my poor planning would be the subject of a post mortem.
Source: I have been in management and executive positions for 15+ years at startups ranging from super small to rocket ships IPOs.