CT, I have read and believe you might have also mentioned that maintaining muscle is much easier than building it. With maintaining being possible with as low as 1/3 your volume though 1/2 is usually recommended.
If one is satisfied with their development is it possible to maintain indefinitely, training 2-3x a week at a much lower volume?
Yes it is but the risk will be to lower intensity/how hard you train. Which often occurs subconsciously when you decide to “train to maintain”…honestly I have not known many people who actually maintained when they decide to only maintain.
But there will come at time, with age, that you will lose some muscle. For some it might not occur before their 60s, for others it will happen in their 50s or even 40s