Is there a default size for a check raise?
Does it depend on the street?
How do we adjust vs different eff stack sizes?
Does it depend on our hand strength?
On the board?
On how our range does vs villain's range?

I've never really learned how to properly size a check raise.
It would be very helpful to have a sort of default to start from and then know which factors make us go smaller or bigger.

In my live games I constantly see people min x/r, so someone bets 20 on the flop and they raise to 40, which seems just ridiculous to me.

I usually try to make my x/r large enough so people can actually fold to them, regardless if I have value or bluff.

I wouldn't be surprised if there isn't an (outdated) TOTM on this or one of those 'major' threads where the fist post can be a bit of a novel.

I think you've hit on many of the factors involved, all of which can be affected by what you are trying to gain by the c/r.

Cash or Tournament?
HU or Multi-way?
STPR left behind
Generate calls or folds?

I think if you're deep you can go 2.5-4x, taking 'the trail' into consideration as well.

In what could've been a critical pot in the Hell/Negs HU match I think DNegs went limp/9x .. of which Hell immediately folded AJ v AQ.

The min c/r is a classic low stake move, but it could mean a few things .. nuts, trying to isolate, cheap pot builder, bluff on a paired Board against PFR IP.

I think the more drastic the difference in ranges the less sizing you need to c/r .. unless you have a POW in tow.

If you go cheap then you may have a domino affect with the remaining Players with each gaining better pot odds as more Players call (welcome to PLO).

Although we preach consistency I think it would be a huge mistake to have a default size without considering almost all of the items you have listed .. especially Board texture. GL

Great questions!

The truth is there aren't great answers. Bet sizing theory is still an emerging field.

The main factors are

1) The polarity of the XR range - some boards call for a nuts/air XR range that promotes much larger sizes
2) The elasticity of their range - sometimes even a very small XR will force them to fold out a lot of hands, other times their range is more price-sensitive
3) SPR

Putting those metrics into practice is not so simple though.

I'm asking a similar question about overbets in the theory forum.

more or less how many nut hands you are raising/how wide for value you are raising

narrow range (like only sets) = very large

wide range (like top pair/combo draws/etc) = smaller

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also depends on the sizing/frequency of the opponent