To sub dial, or not to sub dial? That is the question. in Watch Discussion Forum Posted June 12, 2015 · Report reply My missus bought me a Greenwich commemorative, grand complication. It has 4 subdials. The only time I use them is when it is a full moon then I will look at the top dial to see if it concurs. The other dials are day/date, seconds, and wether it is a leap year, or how many it is till the next and doubles up as a month indicator. The watch is very attractive, but the features are not necessary.