Bit of a waste of time 1 frame less blockstun, chip negating and meter negating..the risk reward is really not in your favour there, especially with special moves. You go to Perfect guard a 3 hit string of cassies and she notices you doing it, does a flip instead of the last hit, gg you got launched because you wanted to avoid 0.4% chip and 1/8th of a bar of meter and be -2 on block instead of -1...
The JG mechanic in SCV at a high level is meant to cause trouble. It makes certain strings dumb to even attempt, meaning you wont take that chip and they wont gain the meter because they get straight up punished for even trying. Makes going for jump ins harder because you can negate their blockstun. Looping shit into itself is gone. It even makes mindgame after you get HIT by a poke. Your opponent wants to follow up with their mids and has to risk you getting out or punishing with that, they have to mix up their options, go for throws or slower less conventional attacks to mess with your timing.
Certain EX specials with a second hit delay would be easy to JG and negate the chip, kit fans, mileena EX sai, erron black stance lows, cage green balls, Kano EX knives, Ex nutpunch, dvorah EX stabs, dvorah f112 would be a risk to use even because you know the timing on the JG to make her +12 cancel now to make her risk something.
Anything predictable becomes a risk, and messing up the JG timing or being baited is a fair balance to that risk. At super high level the game becomes a lot more solved, you cant go yolo and you cant play on a flowchart.