A bit further back, both Barry Nelson and Jerry Orbach had histories of staying with shows a long time.
Barry Nelson did light comedies like Cactus Flower and Mary, Mary for a couple years when everyone else was gone in a year or less.
Jerry Orbach did Promises for two years and Chicago for two in NY and another year on the road. He did 42nd Street for maybe 3-4 years until his salary went so high that Merrick didn't renew his contract.
Marian Seldes did the complete run of Deathtrap in the 70s, no missed performances and no vacations. This was over 4 1/2 years counting pre-Broadway and previews. I have heard this is a Guinness record. [Spoiler] Since she didn't appear in the 2nd act, she wrote a memoir in that time.
Patti Lupone played Evita for 20 months or so when it first opened. Barbra played Funny Girl for about 2 years from out of town opening until final performance. Lansbury did Mame for two years.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher