I'm not quite sure what the limit is per individual role entry (in terms of lines/characters), There is no chapter limit unless you're abusing the command (per Nalasul). In this case, you're clearly not. You just have a longer than average role, and that's fine.
If you're using mudlet, you can use the formatter to get a reasonably sized chunk for a 'chapter' and then use the 'role queue' command to queue it up. Once you 'role send', if it's too long, it should tell you. You can edit the size of your chapters accordingly.
Also, as long as the role hasn't been graded yet, you can delete previous chapters if one seems too long or you thought of a better way to section it out. I did that last time my 'final' introductory empty seemed skimpy compared to the others.