Your question is difficult to answer not knowing what he is briefing you for.
At $70.00 per hour for ground briefing my only suggestion is only you can really make the decision as to the worth of the briefings.
I personally have never ever given ground briefings that came anywhere near those times.
You must remember the above are only my thoughts on this subject and I may be way off base in my opinions so take them for whatever you may think they are worth.
