I know people who went on low dose just long enough to get the androgynous traits they wanted (less body hair, small breasts, etc), and then stopped when they were satisfied. I don't know if they take antiandrogens to prevent revirilization though.
I also know about people who went on low dose and planned staying on low dose, but then ended up fully transitioning once they realized how well they responded psychologically to HRT. In addition to medical reasons (not overwhelming your system with a massive amount of hormones out of nowhere), starting out with low dose is a good thing since it can help the person decide the path forward. Some people who plan on fully transitioning also find out the opposite - that low dose works better for them.
Lastly, I'm aware of people who have stayed on low dose permanently, never socially transitioning, but remaining part time or androgynous.
Of course, a spouse would probably notice the changes on a long-term low dose regimen (one person I know was busted, but the spouse tolerated it - I'd highly recommend notifying your wife), and possibly also friends, but the changes will often be entirely possible to hide. Often, you'll just look younger. At worst, you might have to wear loose shirts to conceal breast development. Facial hair won't change much without hair removal, and it's not like most people will notice if you lose some body hair. It can absolutely be done.