Mart, there is no secret, and your speculation about picking times, although it might seem right, is wrong, in my experience at least.
Picking leaves off plants, rather than cutting, is as quick if not quicker because the act of picking outer leaves rather than cutting across the top results in faster and bulkier re-growth, so the next picking is quicker (leaves are a good size), and in plants living longer. I find that picked plants go to flower later than cut ones. Grenoble Red lettuce sown September is productive until June – not possible if it were cut.
Repeat pickings are bulky and go on, and on, and on. Hence we are still picking off a range of salad plants sown last September, around 16kg from the top tunnel this morning (measures 18×30 feet), and we picked about the same amount off the same plants exactly a week ago, and the week before, etc (much less in midwinter though). Time taken this morning was about four man/woman hours. No planting costs since October, hardly any weeding of the undisturbed soil: that saves time too!
The numbers you quote are just to give an idea as time of year, plants’ age etc all vary the results.
Please let us know if you find a better way, including all time for extra sowings etc.
And… why would it seem harder work to pick than to cut?