You just can't. Sorry does my head in. If you need realism in training. Need to be in the area you are going to fight have access to every tool you could conceivably use because otherwise you will not be able to fight. Then kata does not fit that module. So I am sure you can give the value of kata based on its own merits but let's see you give the value of kata based on these merits. Sparring isn't a necessary part of self defense training. Beyond that, it is detrimental BECAUSE we revert to our training under duress. Unless sparring allows the person the opportunity to de-escalate, escape, evade, use a weapon, improvise a weapon, use the terrain etc. Does sparring usually contain these and other real world elements (lighting, environment, multiple attackers, starting from a position of disadvantage)? No. Does scenario based training contain these elements? Yes. Do you spar with the possibility that other attackers will join the fight? Do you spar with the possibility that the attacker(s) will have a weapon? Do you spar with the ability to use a weapon, conventional or improvised? Do you have the opportunity to de-escalate the situation so the sparring section doesn't even happen? Do you have the opportunity to escape or evade the situation prior to or during the sparring session? Do you spar only in a well lit, open space? Do you spar with a specific rule set that both of you have agreed to abide by? Do you spar only on a dry surface? Do you spar only indoors? Do you spar on stairs, in an elevator, inside a car, in the parking lot between two cars, on a slippery surface that slopes? Do you spar to a conclusion i.e. you have escaped the situation or the opponent is no longer able to continue the attack? Do you spar starting at a position of disadvantage i.e your opponent is standing over you or behind you?