Should I increase the share pool size?

I ran the AWR reports in one of the database and returned library cache hit ratio as 88%. I immediately thought of increase the shared_pool size. My AWR snapshot interval is 1 hour. But for this one hour only 0.46 min is db time and the rest of the time is idle time. Is this report representative? Should I increase the shared_pool size anyway? If the database is mostly idle, the library cache yields 88%. If the database gets busy, will the library cache hit ratio get even lower percentage? Any advice? This is a 10.2.0.4 version on linux server. Thanks.