Having flown LHR- MIA -LHR twice in Nov and Dec also to LHR-BGI-LHR this month not on A380's. I find delays mainly down to passenger checks ensuring the correct paperwork to fly due to not using VeriFly. This was starkly brought to my focus at BGI as I waited to be last to check in due to the broken queuing system, and a high load. it took over 3hrs for all to be checked in with 4 desks operating and my observations were some passengers were taking over 10 mins to get their boarding passes with mobile phones furiously being typed into. What would have made a difference was someone checking the queue to ensure only those with the correct paperwork or have completed VeriFly correctly, and if not getting them to complete paperwork whilst queuing. This was my first time at BGI so this may always be the case with check in even before COVID.
John