Mike James Brown:
I find the pain becomes a huge distraction between the 40-50 mark and so I don't wanna 'burnout' by facing 4 times 50 mins a day.
While there may be some merit to be realized in sitting through pain, when practicing for realization of the truths of the Dhamma I prefer to eliminate the distraction of any pain by adjusting the body so as to eliminate the painful position.
If needed, use a chair or sofa to meditate on. Nothing is set in stone regarding sitting the traditional lotus or half lotus position (or even just the cross legged Indian style). Also if needed, adjust your legs whenever numbness or other pain begins to set in, and don't even give a second thought about having done so. Just get back to the object of your meditation (e.g. the breath or whatever insight object you may be examining).
Mike James Brown:
However, with so much free-time I'm thinking of sitting for 40 mins about 4 times a day.... Do you think I should push for longer sits (but less often) or shorter sits (but more often)?
Forty minutes to an hour is an ideal amount of time to spend in meditation, conditioning the mind for discipline. Of course, the frequency is totally up to you the practitioner. Do whatever you feel comfortable and beneficial doing. I found three times a day (morning, noon, and evening) an hour apiece to work well for me earlier in my practice (it gave me time to get other things done in between). At present I only sit twice a day for an hour and a half total (one hour in the morning and a half hour in the evening), mostly in contemplation (
vipassana) rather than calming (
samatha). I find time spent in contemplation (reflecting on whatever is going on in my life or anything I wish to examine in more depth) to be most beneficial for me. But each to his own.