I've also been playing with the same group for 25 years this month, though the group itself started several years before I joined. Of the 7 people currently in the group, 3 of them predated me.
We had always switched off between different characters (and, sometimes, different games entirely), though most of the characters are all in one continuing campaign world. The most "senior" of those PCs are now around 17th or 18th level.
We don't play as often as we used to, because we're spread out across 2 states now. Once upon a time, we played almost every Saturday. Now, we play about a half-dozen times a year (though, two of those "times" are marathon gaming weekends).