Keep doing it until you get no more joy from it - hopefully never!

Plus, it never hurts to find a younger singing guitarist (maybe in his 50's or 60's!) that can drive and carry your keyboard for you (just get a light one!!). Musical dialog is what keeps the juices flowing - you only get so much listening to yourself solo, and start to fret too much about the slipping of skills.....
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An arranger is just a tool. What matters is what you build with it..!