Good on you for following through! I know how hard it is when you think of how them being disciplined will affect your day too (like the possibility of me having to carry DD home, which i would have if she'd genuinely not been able to make it herself).

I'm not sure i'd give them back for good behaviour, in case it confuses the issue, kwim? Like is it about generally being naughty or not putting your toys away? Will he know they got taken away because he didn't tidy them, and if he does will it make sense that he has to be good to get them back? I think i'd just keep it really simple - don't tidy toys = don't get toys tomorrow. No complicating rules or factors, just that.

Not sure i'd mix it up at this stage, though you COULD implement a rule that anything he tidies up he gets tomorrow, so if he only puts one toy and one teddy away that's all there is tomorrow. That way how much effort he puts in DIRECTLY affects how many toys he has. Also did you tell him today that you would take them away for a day? If you told him and then you do it that teaches "mummy means what she says" but if you didn't warn him it might teach "mummy can be unpredictable"...?

Bx