This is just from previous experiences. The website can have problems - espcecially during major seat sale promotions. Im sure this is currently being looked at, as there will not be the resources at the airports to have check in desks let alone check in staff should the system fail one day.
WebCheck is currently open from 14 days up until 4 hours. It should maybe be extended - perhaps you could check in online as soon as you have booked your flight. This would ensure the majority of passengers do it.I dont know how the newskies system would cope with this, but it is a possiblility. Currently I think U2 allow online check in fom 3 months prior to departure.