DOF And The 45 mm

PS. I forgot something...

I don't get everything right first time and if I think that camera settings may be an issue I try and take more than one shot... You don't have to fire off shots machine gun style but no one could expect to get the DoF spot on every single time so why not take a couple of shots at different apertures, for example start at f1.8 and then quickly stop down to f2.8, f3.5 etc. and pick the one that looks best as the keeper?