This is a hard question to answer (Can't say any specific amount of RNG since every fight could lose you time because of gen 1 misses ect)

However the main parts of the run where you can lose time or die due to RNG are:

• Mt moon encounters
• Misty fight
• Cans
• Gyarados crit (x2 if going for silph red bar)
• Agatha and Lance can both screw you over

Compared with other pokemon games Red glitchless has few places where you can die, and most deaths don't cost much. Gyarados crit is the only thing that you really need to worry about, unless you are going for a really good time.