Except for newer powders, the data in older manuals is typically better. Too much litigation influence in our sport these days.
While there is a grain of truth to that, I believe that as a responsible handloader, I should use the newest most up to date data I can find.
I keep old data in my library, and consult it quite often, but before I load from that data I verify that it is still a recommended load. I've been around long enough to know that components change, and issues come to light. Books have typos, and addendum's exist.
2400 powder from yesteryear is not the same as todays data.
Some published Blue Dot loads are no longer recommended.
H4831 was surplus, then newly made in Scotland, now made in ???
Pressure testing is more accurate than ever, piezo vs copper crusher.
Weight and internal volume of same brand brass is different. Sometimes the design has changed.
Primer technology has evolved.
However I do have issue with "new" manuals. Some of the less popular calibers just recycle the old data, issue after issue. And when you come across some discontinued powder, the old books are the only ones with data.
However my Speer #9 is retired, it contains some hot data, along with loads with unsuitable powders.
I've been waiting for #15 Speer, my latest is #12. I went to buy #14, then realized it wasn't that current.