We cut midpoint progression from 15% to 10% between grades and I would not do it again

Same experience in a Nordic bank. The promotion increase guideline is what broke for us. With 10% progression and a guideline of 'up to 8%', almost every promoted person landed below the new minimum's 10% penetration mark and managers felt cheated on their behalf.

I would push back a little. Narrow progression is not the fault, the 16 grades are. If your evaluation method cannot reliably tell grade 9 from grade 10, you have more grades than you have distinguishable levels of work. We have 10% steps but only where there is a clear level definition behind each one.

How did you handle the conversion? I ask because we are being pushed toward the same change and my worry is the one-off cost of bringing people to new minimums.

On conversion: it cost us 0.4% of payroll to bring people to new minimums, which was less than feared. The cost came later, in regrading. And I accept the point about level definitions. Ours were written after the grades were drawn, which says it all. We are now collapsing back to 12 grades with progression widening from 10% to 16% as you go up.