Work other company on days off

Steve-o:
Anyone ever done agency on their days off when on a 4/4 shift pattern or something similar? Talking about people already doing a driving job and for whatever reason their main employer offers crap overtime wages/shifts etc

Wondering if so, then how did your main employer take it?

Is it just me who finds it very sad that a driver working this shift pattern which includes Saturday and Sunday cannot earn enough to live on and needs to find other work for his days off.