I think I speak for many artists in watercolour when I say that almost every painting is a battle. The unexpected happens so often and the challenge then is to actually bring the painting to a conclusion. Maybe this is why I like watercolour so much. Fate takes a hand and I have to find a way to turn it to my advantage. Although we sometimes think we know what we are doing, it only takes a very slight miscalculation on how dry a part of the painting actually is and the next brushstroke can either ruin the painting or give us a chance to show how clever we are to rescue it and turn it to our advantage.
If I did have total control, then maybe my paintings would all turn out to be of a similar standard and I wouldn't have the little hiccups that can sometimes push the painting in an unexpected direction. Those are the serendipitous happenings that can make it fun and enthralling or in the worse case, more material for my waste bin.