It takes an average of 70-80 seconds to build LotD and 25-30 seconds spent actually using 3 Nastronds. Nastrond only accounts for 5-8% of your raid damage while the vast majority of it actually comes from FnC and WT which are about 16-20% each, more so now that they added a 50 potency buff which will now make 2nd positional do as much as a full thrust.

Entering LotD more often is not something that I personally want. I would rather just have Dragoons hit harder per GCD/oGCD for big numbers because DRG is in a pretty good spot at the moment.