@SeasonedRP I understand that the older guy is effectively caught in a fork. One one hand he recovers less effectively. On the other hand he also responds less well to the training stimulus -the number of genes whose expression is altered is much reduced. There are a number of studies on this in mice and men. Here is one such article. Its worth reading a few. www.sciencedirect.com/science/article/abs/pii/S0047637400001780

This means that as you age, you have to use your resources wisely. Some age earlier than others and in the end if you know your body, you should be able to pick up on when things change for you. In the late 40's there is usually the most pronounced change for men and things then carry on gradually declining until around retirement age mid 60's when you take another more pronounced dip.

Young guys only need a small stimulus to get gains and they recover fast. Its why young tradesmen who don't even do any sport or training usually look great on a construction site in summer with their tops off -work alone is enough stimulus, they can go out drinking after and still look great. When older tradesmen do not do any sport or training they look worse than office workers when they take their tops off in summer. The job is actually driving these guys down as they are not fit and can't recover from it. The stress usually makes them fat as well and they often live less long than desk jockeys.

There is no need to change things up until you see you need to. Then it becomes a case of making the stimulus felt enough yet not slamming yourself beyond your recovery ability. An extra set is said to sometimes be the answer but it will have to be lighter or less frequent or else it will push you too far into muscle damage to effectively recover in time for the next session.

I am not really a lifter, so I can't say the exact things lifters should do but the aging problem of poor recovery and poor stimulus response is the problem one needs to work around somehow.