@ingorohlfing I think it's still feasible; boils down to being a time-stamped and public lab notebook
Reg 1: "we don't know the exact shape of the data yet, but we think it's gonna have X, Y, and Z. We're gonna do [Plan] if true"
Reg 2: "The data had X and Y but not Z; need change [Plan]"
I think this applies to the registered report case, too. Diff fields are gonna have diff norms for how much you oughta know about your data columns a priori, but within that context can make judgments fine