scheduling workman overlapping periodic tasks

with worker, wholly perform assign during (but switch between tasks instantly)

given list tasks,

-- tangible "n seconds, each m seconds" (eg, 5 seconds each 3600 seconds)

how i best starting times count any task?

if each assign "1 second, each 60 seconds", any have an unparalleled starting second, count enormous (steady state).

if "1 second each 4 seconds" "1 second each 3 seconds", outcome be: " 0, enormous 3, 3 times"

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hopefully simplest form

if already i have list tasks, elaborated "start second array times", duty returns: {start, count} an additional {n seconds each m seconds} assign feeling like?

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(slightly some-more challenging form --

if instead "n seconds each m seconds",

the tasks tangible "n seconds each l..o seconds",

where i collect array m operation l - o (but have dedicate m until assign finished),

would grant improved workman utilization?

how i select best 'm' ?