If a person is working a full week they deserve a wage, not JSA.
JSA should be reserved for people who are currently not working but are actively seeking work.
The very most which should be enforceable is 7 hours a week (one full day) which at minimum wage works out to about the £45 a week (if this is really to get people to 'earn' the JSA payments), anything over that seems to be missing the point about what jobseekers allowance is meant to be for (ie, people who are not working).
Who whole thing isn't that sensible anyway, as it ignores the fact we currently have a deficit of available jobs - which regardless as to how many penalties they plan on inflicting on people seeking work it will never get everybody into employment.
Yet another short-sighted idea, not backed by any evidence meant to appease the "average 'Joe' on the street" who feels hard done by, who takes an element of pleasure from knowing those further down on the pecking order are getting shafted.
Schadenfreude at it's best.
Why 7 hours?
Why not account for the fact that 'long term' unemployed have had a year or two of payments... getting occasional work placements is hardly that unfair given the the amount they've received over time