It works great if nobody ever leaves or dies or takes vacation. We try to discourage siloization of projects and emphasize cross-training - it makes the job more interesting, gives people more/better tools to solve problems with, etc. And anytime the business objects we mention the project where X left and how painful it is to get new anything added/enhanced because none of those tenets were involved.
However, all bets are off with offshore contractors. Some want to learn, some simply don’t care and will do the bare minimum.
One of my bosses has a concept of “T-shaped developers”, which means you know everything a little, and have depth on one thing.
7months: ouch, sorry to hear. I wish I had some words of wisdom to share.