Do you use white balance card while photographing using speedlites? Or is the light source already balanced?
I do use it with non flash sessions. But does it make an impact with speedlites?
I gel 99% of the time, gelling while shooting raw IMO makes post processing easier when it comes to WB. The only time I do not gel is when I use a studio strobe, it over powers the ambient. I only use a grey card when shooting events with that horrid vapor lighting in schools, I shoot available light at those. But anytime a flash is on my camera indoors and there is tungsten lighting, I gel.