Here's how you can use the information stored in the jobs to get a running duration in seconds for each job that has a valid StartDateTime and FinishDateTime:
% Choose a cluster object. Here, I'm using the 'local' cluster
c = parcluster('local');
% Get start and finish datetimes as cell arrays
fdtc = {c.Jobs.FinishDateTime};
sdtc = {c.Jobs.StartDateTime};
% Work out which have valid start and finish times
ok = cellfun(@(x,y) ~isempty(x) && ~isempty(y), fdtc, sdtc);
% Create datetime arrays from the cell arrays
fdt = vertcat(fdtc{ok});
sdt = vertcat(sdtc{ok});
% Get the running duration by subtracting start from finish.
runDuration = seconds(fdt - sdt)
