I dont think that is true at all Kit, I dont know if you have different rules in ACBL-land, but if what you say is true, then everyone could just say "I always planned to bid like this". How would that work in practice? Do you write down your plan ...
Either they bid 7NT knowing ♦K is off. quiz: How many diamond tricks do you think they need to make 13?
Or more likely they are bidding 7NT with void vs no control, much in the bidding is screaming that this is the case.
In both these cases leading from ...
"This took me some time". Your slow bid probobly awaken your partner, who would probobly have bid 5♠ had you bid in tempo. YOU did nothtig wrong, but I'm pretty sure your partner did. Score should probobly be adjusted to 6♥(x)-1
Why would you want the short diamond bid in 2D? I play it in 2H instead. It puts alot more preassure on opponent since they cant sit back one round and see what happens.