Fairly frequently, maybe every few weeks, I get an email saying either, "Hey, I am in town tomorrow, do you have time to meet?" or "Hey, my friend John is in town tomorrow and wants to meet you. Do you have the time?"

I absolutely hate these emails. And I don't hate a lot, really. But these emails drive me crazy. Here's why:

1. Well, of course I can't meet because I actually plan my days, and I am busy meeting other people and doing my job.

Related: 5 Rude Emails You Send Every Day

2. The assumption that I would have time is kind of insulting, implying that I am waiting for these emails to come so that I would have something to do.

3. But the worst part is that it actually shows a lack of thoughtfulness and empathy on the part of whoever sent the email. It shows that they don't value me or my time, that I am kind of an after-thought, a filler meeting.

Maybe I am overreacting. I don't think this is the right thing to do, and I would say that even asking to meet next week is pretty tight. It really is. People's schedules are pretty full for weeks. This is exactly why I plan work and all my meetings far in advance.

For example, we book Techstars mentors in New York City to come see companies one month in advance. We schedule Fred Wilson, David Cohen and Brad Feld to speak two to three months in advance. We know these folks are super busy and their time is very valuable. That's why we work hard to think it through how to get on their calendars in advance, and be respectful of their time.

Related: 8 Tips for Turning Email Introductions Into Actual Relationships

In general, just because you are coming to town, it doesn't mean that it is a good idea to fill up your schedule. You don't necessarily need to catch up with people you've not seen in a while, or try to pack your days with meetings just because you have time.

I recently took a business trip where I only met with a handful of people and worked the rest of the time. Because my schedule wasn't as packed, I was able to spend more time with people who I really needed to spend time with. And I also got a bunch of work done, so it didn't feel like I lost three days of work.

These days, where we are constantly in touch online, it is not necessary to artificially jam meetings during our trips. Leave a little more time for people you really want to meet with and get some work done.

Why don't we all become a bit more thoughtful and respectful of each other's time?

This is particularly important dynamic for founders who are building companies and building relationships with investors, business partners, engineers, etc. Be more thoughtful, deliberate and get an edge just by planning a little bit ahead.

Related: Everything You Need to Know to Avoid Business Lunch Blunders