Should asana and dharana generally be done separately? I've just seen Jane Wolfe's Cefalu diary where they are performed separately.
Currently I practice both combined daily for thirty minutes (at least once a day, twice where possible). I hold one posture while concentrating on one thing - usually a mantra but sometimes a visualised focus - while doing rhythmic breathing (a variation of the four fold breath where the exhalation is twice as long as the inhalation + holding full + holding empty - it's timed with the mantra).
I count the breaks of posture and concentration and note the number and nature of the breaks (such as the content of the thoughts when the concentration drifts) in my diary. Would it be better to separate the two?