Would starting work whilst on UC be a recipe for disaster?

My client is on UC with an LCW element (no DLA or PIP). She says she has been told that she should not expect to be reassessed for another year. She has the opportunity to work 15-16 hours per week in an easy peasy job putting things in envelopes for minimum wage. However because it is paid weekly whenever there are 5 Fridays in a month she will exceed the threshold in reg 41(3). I have read the example of Nigel in the ADM G1035 which suggests cases where they might not do a new WCA but wondered how in practice this is working out. In practice do claimant who have LCW and start work end up being sent for another assessment? Obviously she has got a lot to lose.