Refreshers, dear boy, refreshers ! Barristers are paid a big fee for preparing a case like this, which also covers the first day of trial. For the second and every subsequent day they are paid what's called 'refreshers' per day. These can be quite substantial, and every day the trial lasts they mount up, at the same rate per day.
And where a case is built on circumstantial evidence, as this will be, there is always a lot of detail, which taken together, is supposed to prove guilt. Now,your task when defending is to chip away at each tiny bit, so that the whole lot together isn't quite convincing enough for the jury. And you never know which bit is weak; you can't pass over any bit.
The jury panel is warned in advance of the estimated length of trial, so that only those who are available for months will sit. This does tend to mean that the jury is comprised of pensioners, "housewives", and the unemployed, but it's still a jury.