I have a similar approach. I have dosed several epidurals followed by a spinal for urgent c/s and have never had a high spinal (not saying it can’t happen, just haven’t experienced it). If the patient has an epidural in place that has required a lot of trouble-shooting by the anesthesia team throughout the day and she has never really gotten comfortable, I’m pretty quick to pull it and do a spinal in the room, usually 1.5cc. If she has an epidural and has partial relief, I’ll try dosing it, if she’s not getting the block I want after say 10-15cc, I’ll pull it and place a spinal, maybe ~1.2-1.4cc. Maybe I’m too quick to switch to a spinal, but I absolutely hate limping through a c/s with a sh$t epidural, so now I don’t. Never had any issues.... other than reliably comfortable patients