If you tag a way with lanes=x where x is an odd number, all mappers after using using JOSM will have to deal with a complaint that lanes:forward and lanes:backward is missing. I believe (though I am not certain) that Osmose also generates a bug for every instances of odd-numbered lanes without lanes:forward and lanes:backward. This makes a lot of additional work for your fellow mappers. So, please add the lanes:forward, lanes:backward and (if relevants) lanes:both_ways tags yourself in order to avoid these problems for others.