LAX,
If the scenario you describe happens, then all 12 lanes should be open, tactically there is no excuse for it not to happen.
Strategically, maybe more lanes should have been provided? There are 3 double-decker buses arrive each day, and they didn't start arriving un-announced.
Much of the Manchester forum on PPRuNe is about new services, or increasing frequencies of the services already established. What is the point of that if the airport is struggling to cope with the situation existing at present?
A colleague of mine recently flew LSGG-EGCC, arriving mid-afternoon. It took 30 minutes longer from arriving on stand at T1 to his home in Bramhall, than it did to fly from Switzerland to Stand 6.
The airport, as Mr A Tis observes, sadly, seems to be constantly playing 'catch-up'. Car-parking is now a major issue, and will only get worse as 'Airport City' is developed. Public transport to anywhere south and east of the airport site is virtually non-existant. Due to a lack of foresight/investment 20 years ago, it has in 05R/23L, one of the most inefficient runways in The U.K.
The airports own FB page strongly advises people to turn up 3 hours before departure time, that doesn't include travel time required to get to EGCC. I can foresee more pax opting to go via Yeadon or John Lennon for certain services. Had it not had its misfortunes over the last few years, even Blackpool would have been a viable alternative, being only an hour by road from Manchester city-centre.
The 'Halcyon Days' of 'MIA - Serving the business-end of Britain', and Manchester Airport, 'Gateway Airport', (with the 'Terry's Chocolate Orange' logo), seem to be, (like the aircraft that carried that name), long gone.