Resource Histrogram

When allocating resource on primavera the histrograms never seems to come out as a true reflection of the resource needed.

Example:

resource calendar is a 10 hour day with no breaks and there is 5 jobs planned all taking 2 hours and 2 men, therefore i plan to do the jobs one after another so on this day i require 2 men to carry out all the planned work. Primavera histrogram will show 2 men which is good.

However if 2 of these jobs had to be done at the same time, say between 08:00 and 10:00 for whatever reason i would therefore need 4 men on this day to complete the planned work. Granted 2 of them will not be needed after 10:00 and the other 2 will finish 2 hours before the end of the working day, but to complete the planned work at the planned times i need 4 men. Primavera still says i need 2 men, i think this is because of the calulation behind it, however this calulation does not take into account where the work is planned.

Am i missing something? Like i need to show histrogram in hours rather than days? as it seems to me this is a massive draw back to primavera if it cant even tell me the correct number of resource i require.