Briggs tuning: dGDF#A Can play tunes in G (1 sharp-F#) or D (2 sharps-C#, F#)
Rice tuning: eAEG#B Can play tunes in A (3 sharps-C#, F#,G#) or E (4 sharps-C#, D#, F#, G#)
So, for example, if I am tuned Rice, to play in key of A, I just read the sheet notes; if playing in key of E with Rice, what do I do?
When playing in the key of E, just play the notes as written. An E string in that tuning is E regardless of whether you are playing in E or A.
If you are learning to play the jigs in the instructors, that is one issue. I usually leave my banjo in Briggs' tuning, and transpose the notes as I play Rice, Buckley, Converse, etc. The complication comes when you are playing with other people. If they are reading the same music you are it is important to be playing in the key that is written. I usually leave my banjo in Briggs' tuning simply because more of the people I play with have instruments in G/D.