Now he has his little black book.

Collingwood's All-Australian will reference his notes in that book about Shane Mumford ahead of Saturday's preliminary final against GWS at the MCG.

As Grundy explains it, there will not be exhaustive observations about how Mumford goes about his game, or do's and don't's for their ruck duel.

"It's just thoughts, feelings or little things - it's more just when I see something, I will write it down. It's coaching myself," Grundy told AAP.

"It's not necessarily things to do against opposition, it's observations, like 'This is how you felt - why? Focus on this, do this'."

Grundy said going away from scouting his opponents and then going back to it were deliberate decisions.

"If you start perceiving, or projecting or thinking about the other person too much and you forget about yourself, you're already a step behind," Grundy said.

"Then in the middle of my career, I thought I was losing sight of what I'm doing well.

"I stopped caring about what other players are going to do.

"Then probably last year and this year I found a really good balance. I feel like it's a bit negligent if you do not take note."

Grundy calls himself a student of the ruck craft, rather than a student of the game.

Renowned as a quirky personality, he loves to sit down on a spare Friday night and watch the footy like any other footy fan.

But he won't obsessively watch all eight other games on a weekend.

For one thing, there's his ongoing university study. Also, there's life outside footy.

And tied in with all that, there's the perennial "to-do" list nagging away in the back of his head.

"Some weekends I will just want to do nothing, but I know there's a list of things I need to do," he said of his down time.

"Sometimes I just give myself permission to have a weekend (off) and then some weekends I will smash out my to-do list."

Australian Associated Press