I believe that everyone can communicate with their spirit guide(s).  I believe that everyone does communicate with their spirit guides on some basic level.  Most people just force their guides into the back of their minds and try to push them away because it is not "common practice" to communicate with ones guide. I'm not sure how many guides one person can have.  I believe that the number (to a certain extent) fluxuates, depending on your situation in life. However, I maybe wrong; or possibly, someone has advice to the contrary,but from my experience the number of guides varies from person to person. A person can have any where from one to one hundred guides ... and possibly even then some (albeit it would be pretty difficult to maintain connections with over 100 guides...).
As far as communication is concerned .... it is something that comes with time, patience , and practice (also having a well adjusted ear helps=)...). There is , however, simply no way around the "practice" part of it.  Just try to listening to your instinct WHATEVER it says ... your instinct is the muted voice of your spirit guide.  Listen to it. It works only in your best interest and for you only. You'd do well to live by what they tell you.

I am not sure Everyone has spirit guides.  That is a bit of a stretch.  

A rank materialist is so involved in this earth life they take no heed whatsoever to the unseen world.  Any buzz or touch would be ignored and dismissed with another explanation.  How long could a guide remain in that position of ignorance before deciding to move on to someone willing to listen?

A poet, a writer, an artist, a doctor, a philosopher, etc. all have what is commonly called a muse.  This is the still, small voice within that helps them accomplish their chosen creation.  Creativity is inclined to bring the unseen help.  Would they stay once the project was complete?  Perhaps we could consider the spirit guides in any creative project as a specialist in the particular topic and they can and do move on.

Perhaps this where many guides is considered?

In mediumship work we attune to the spirit guide of our own mediumship.  They help us to acclimatize our body, mind, spirit to the spirit realms and make that attunement with our spirit guide.  It is in communion with our guide that all spirit work occurs.  A psychic may call this their own higher mind that brings through information for use for self or others.

Hmm... perhaps I should rephrase that then with :
"I believe that everyone has the potential to communicate with their spirit guide(s) at some given point in their life."  Whether or not that they use the opportunities they are presented with is another discussion in and of itself.
The concept of spirit guides remindes me of manufacturing.  When someone is working on a specific task they work for a certain number of hours and then they are done for the day.  After the finish someone comes to replace them.  After that person, another person, so on and so on. Eventually the person who was working during the first shift comes back on and continues.  So the cycle starts all over again.  The Mayans believed that time was cicular, and since "time" is considerable diffrent for spirit guides then it is for us (it's not as if they run on military time) then who's to say that they don't follow some sort of pattern of disappearing and then re-appearing.  I do believe that we are never left alone to wallow without any guidance what so ever just because, in our human ignorance, we scorn guides and refuse to heed their guidance from time to time.  However, I do maintain and believe that the more one ignores their guide the harder it is to tune in when they need it most.

I am not sure I go along with the circular time theory.  But spirit guides do come for a specific purpose and then move on.  Others will and do step in to do their project with the receiver.

Yes, we all have guidance throughout our life.  We have a Guardian (some call them angels) that guard us through all our decisions.  Guides come when we work together.  

God bless, J