I can't realy say, instructions generally suggest a limit of 15 seconds, but I supose that is to cover extreem situations.
Personally I sugest you buy shunts, those metres can be used to measure across the shunt on mA mode, but most DMM's have an auto power down function. Discrete digital metres can be purchased to mate with shunts.
For 10 amps I would suggest analoge metres, they are more impressive for wind and have their own internal shunt. They will cost a bit more than those DMM's but they are easier to use/set up, you would just include them as you diagram indicates.
allan down under