When do we use our knuckles as opposed to fingertips for the read?

Here is my master summary

How to read
- Take "directional read" of middle 2/3 (stand over and face the direction the ball will travel over/to)
- Play biggest slope

0-3 feet
- Any putt within three feet and 0-3% slope does not play more than 1 inch outside cup (at 3 feet, 3% break is 1 inch outside cup)
- Don't use fingers less than 3 feet

3-6 feet
- Use "pinky read" off cup
- stand with toes at ball
- by Pinky finger 1, ring and middle 2 and 3 (use tips of fingers) off center of hole/flag
- Overreading short putts? likely flexed arm too much, extend arm more

7-10 feet
- Use "standard finger" read (Center/middle knuckle of pointer, middle, ring finger)
- At 7 feet, cross over from pinky read to standard read
- This is where you start "standard read" - index to ring finger, more across center/middle knuckle

7-20 feet ("mid range") - middle knuckle
- Obtain directional read for middle 2/3 along line ball will travel at 3 points
- 33% of putt, 50% of putt, 66% of putt
- When over 10 feet, stand one foot behind ball to line up standard read
- When in doubt (for longer putts), play more

> 10 feet (transition point where you stand 1 foot behind ball)
- Standard finger standing at ball is an under read, so you go a foot behind the ball and do a standard read
- Have arm reading putt with elbow in belly, be careful of bending arm too much

>20 feet
- use standard read with base of fingers/proximal phalanx (because they are widest and we want to err on side of playing more break)

>30 feet (Long putts)
- This is where 3 putts more common
- An under read will triple the distance to the hole (eg. reading 1 foot off will result in 3 feet from hole), so we want to cheat a little high
- Read biggest slope in the middle third of putt along line ball will travel
- Should center putt dispersion around hole (need some short and long)
- To over read, add a little arm bend or slightly over read