As my current class of students expresses their annoyance and dismay at these 'visits,' they always ask me why I'm not more bothered. Typically, I simply answer with something along the lines of it's nice to have visitors and catch up. Every year, by about January or so, students in my current class start to ask if they can stop by "all the time next year too?" Yes, of course, I tell them; then my class next year can be annoyed!
I know this happens with many teachers; especially in my building, as there are a multitude of fantastic teachers at my school.
And I don't write about this today as a means of bragging...
Simply put, I feel very blessed. Blessed and honored that kids - teenagers - take a moment to say hello, share a laugh, tell me a story, etc. It's a hidden, unpaid perk of this
While some times aren't great for visits - tests, deep lectures, speeches, etc. - I will never frown upon a former student's shadow darkening my doorway; it's a blessing.