I think that's a fair point Arjan. It's often mentioned that Zandvoort in 1971 was the big chance for the 56B (and Walker), but it can't have been easy. Even with the advantages of FWD, and Firestones, handling throttle lag and braking on a slippery track, at a circuit with a long straight ending in a hairpin...
Out of interest, apart from practice at Zandvoort, I wonder how much testing Dave had done in the turbine.
I was at that race although round the back of the circuit. It was noticeable how quick Walker was in the first few laps and I do wonder how well he would have done if he'd kept it on the track. It was a fairly big accident as he ended up in an advertising hoarding. He wasn't the only one to go off there. Chris Amon, Jackie Stewart, Francois Cevert and Nanni Galli, plus a few others all spun or crashed, although I think they were all on Goodyears and not the Firestone's that Walker was on. I don't think the 56B had any engine braking, so that possibly didn't help.