But you can; whether you should, or if it is a decent thing to do, is a different matter. Placing an upper limit means that you are less likely to be rescued a

But you can; whether you should, or if it is a decent thing to do, is a different matter. Placing an upper limit means that you are less likely to be rescued at all, if the potential rescuer happens to not be a nice person (or is very risk-averse and rescuing you involves some risk). In other words - if the person is nice, you do not need to have any limits, as they would not abuse the situation anyway. If they are not nice, with the limits they will not rescue you, but without, there is a chance that they will be overcome by greed and so will rescue you.