Friendship is a full-time job, although it is one of those fun tasks that one can perform all day in practice has its problems.
One of the main problems is to match your schedule with those of your friends. In general you are with gusts frequent periods in which a sub-set of friends than to others. But when you hang out with someone, what are your options? What happens to friendship? It certainly can not flourish and improve insulation.
Email, IM, twitter, telephone and, in general, communication technologies help, but do you have the discipline to reach, with the right frequency, to everyone on your list of friends?
And, already entered in question, how many levels or circles of friends are you? How many of those friends know you well, know your desires, your fears, your family, etc..?
ANSWERS I have no good or satisfactory answers to these questions, do you?
