I'm not aware of any hard-coded limit on the number of log backups that you can include in the log anaylsis, please correct me if I'm wrong.
If anything bad happens, it's probably because you don't have enough resources available (RAM, disk space...). Log Rescue can pound your local disk caching extracted information from the log file and/or backup files.
There's a funny issue to do with usernames in the SQL Server logs. Sometimes the username is not recorded, in these cases, log rescue calls the user unrecorded because the log identifies him with a userid of -1. For users that can be resolved to a user name, Log Rescue identifies any user that is part of the db_owner role as DBO. Otherwise, normal SQL users are listed in the analysis.
I hope this helps!