That's helpful, thanks so much!

What type of hints are most useful from your POV? Are they more direct (i.e. here's a free box in case you are stuck), or more suggestive (e.g. "Pay attention to the naked pair in the third grid")?

With the latter, striking a nice balance between hints which are simple to articulate without esoteric terminology is important.

Really appreciate the pencil mode pointer, I'll check it out.