>>20170Both of your questions need more specificity. There are a lot of different martial arts with different combat emphases (punching, kicking, throwing, etc.) and different strategic goals (winning a sporting competition with rules, defeating a fighter in a warzone, defense in non-consensual violence, etc.). What's appropriate for one may not be useful for another.
On the point of reflexes I'll say that that unless you're a professional fighter trying to compete at the top echelon of your sport, most people are deluding themselves that a) they can meaningfully improve their reflexes at all and b) that reflexes are actually an important aspect of defensive ability. A human being simply does not have the physiology to react to an incoming punch already halfway to their face in time to deflect the blow if their hands are in their pockets. Having your hands already up in a guard position and being able to recognize the signs of aggression and what a punching motion looks like eclipses any kind of training you can do to improve raw reflexes.