One of the other things to consider is the actions of a human. A player does not sit at their computer for even two hours without some form of tab-checking, interaction with an external application, or even a minor AFK every couple of minutes.
Most bots are programmed for efficiency and at the expense of appearing *human-like*, to use the phrase, they tend to chase the xp/hour rather than a genuine human approach. I know that if I focus on my interactions with the RS client as a human, I take an extra 5-10 minutes per hour to do what a bot could do in that time, simply because I'm browsing Youtube for a new song to play, or scrolling through Facebook.
It would seem that the key to a successful script is human-like response time, human interaction (speaking in chat, randomly), checking skill tabs, experience rates, and taking the odd 5-10 second pause every 5-10 minutes. It would show up like a sore thumb if there's players attempting to kill Hill Giants and burying bones in the exact same way for five hours straight.