Isn’t it better to do one thing at a time instead of chanting inattentively while doing other things?

From: sourabh
i see devotees of iskcon chanting in whatever way the can.
i mean they chant while walking,talking,speaking to someone,working on mobile phone,looking out of the window of train nd chanting
how do u justify such inattentive chanting? wouldnt it be better to do 1 thing at a time?