Out of interest, what do you use if it's not caustic based? I have done trials with high pressure industrial steam cleaning machines and they never shifted the baked on deposits.
Are you purely domestic or do you do commercial as well? We have a lad in our area does domestic only and charges £24 for single oven £12 for hob, but i know he has a caustic bath in the back of his van.
I have heard of others who use sonic pulses to break down the deposits, but have never seen this in action or advertised.
We get asked all the time by our commercial customers about deep cleaning of kitchens, but I have yet to find a method, other than caustic that is effective and efficient for large areas with years of baked on carbonised grease