They're definitely way more complex than the mere adding up of speech acts, but they provide a systematic and deeper way of unraveling the whole range of discourse patterns we observe and participate in everyday.

By intuition, most people might think that our utterances are totally random and will hence not follow any rules, while others might believe that most of our discourse can be neatly classified and described with prototypical act sequences. For me, I take the less extreme view - for a specific speech event, I believe there are rules and generic structures involved, but these are heavily influenced by a myriad of variables both within and across cultures.

Take job interviews, for example.

In America, it might be crucial for the interviewee to express his or her ambitions, and be confident and proactive in the conversation, but employers from other cultures (maybe Chinese?) might instead be looking out for qualities of modesty, respect and courtesy instead. This will probably result in different rules for this particular genre of speech event in the context of different cultures, although basic act sequences are probably similar (eg. interviewer asks questions, interviewee answers questions, and it repeats).

Within the same culture, there will still be other factors (eg. company culture, job requirements, job position, industry type, etc.) that affect how the speech event will typically unfold. For instance, my sister once rejected an interviewee's application for a boring admin job because he appeared too ambitious and eager - she claimed these were undesirable traits for that job. However, wouldn't it be drastically different if the person was applying for, say, a position for regional manager?

Hence, the same type of speech event (eg. job interview) can have participants having different dress codes, presenting themselves in different manners (be it verbal or non-verbal), depending on various factors.

To end off, here's a funny advertisement on a very extreme way of getting your dream job. =)