On the plus side, people can really set up a schedule that works for them, and be happy about it. Are you a morning run addict? Do it and show up a bit later. Natural night owl? Show up in the afternoon and work into the night. Think prime time is bed time? Show up early and leave midafternoon.
On the down side, flexible hours are a rope you've been given and you have to be a bit careful not to hang yourself. If you take "flexible" to mean "don't bother working as much", you're not going to go very far.
There are a few things that can help your chances of success in a highly flexible work environment:
- Some showing up is beneficial. In order to form the relationships that will make you successful in your job and your career, you need to be around. Get totally off schedule, or work from home constantly, and you'll have a harder time forming those relationships; it's not impossible, just harder.
- You still have to work. It's up to you to get your work done, and you have the added burden of having to set up a schedule (or at least refine one) that gives you the structure you need to be successful.
- Consistency matters. It doesn't matter when you show up, or when you leave, but your coworkers should generally be able to count on you being around at about the same times every day (or week or month or year). That way when they're scheduling meetings, they will know to schedule it for 11 because you get in at 10, etc. If you come in at 7am one day and 3pm the next, you're making your coworkers work a lot harder to include you. Of course, doctor's appointments and whatnot do occasionally happen; just try for general consistency.
- Consider core hours. This is related to the showing up bit. You have to show up when people are there, and generally you need to allow for a few hours of overlap so you can actually have working sessions with your coworkers. It's helpful to have 2 or 4 hours where generally everyone's there. That is when you start to find design sessions, code reviews, meetings, etc. scheduled.
- Be willing to go outside your normal. Sometimes a meeting will be scheduled outside your normal flexible schedule. Well, flexible goes both ways - you get flexibility in your schedule, and your employer should get flexibility in your schedule, too. That means that if some early bird has scheduled a one-time 8 am meeting, well, go ahead and make the effort to come in, even if you're normally an 11am kind of person. Accommodate others just like you ask them to accommodate you.
As with many other things, maintaining a successful flexible schedule is something that can work really well, as long as you're willing to put in the work and remember to compromise. After all, a flexible schedule is for everyone's ease of use - so use it, and be flexible with it.