I've been working in embedded software development for this small startup and our team is pretty small: about 3-4 people. We're responsible for all engineering which involves an RF device controlled by an embedded microcontroller that connects to a PC host which runs some sort of data collection and analysis software.

I have come to develop these two guidelines when I work with my colleagues:

1. Define a clear separation of responsibilities and make sure each person's contribution to the final product doesn't overlap.
2. Don't assume your colleagues know everything about their responsibilities. I assume there is some sort of technology that I will need to be competent at to properly interface with the work of my colleagues.

The first point is pretty easy for us. I do firmware, one guy does the RF, another does the PC software, and the last does the DSP work. Nothing overlaps in terms of two people's work being mixed into the final product. For that to happen, one guy has to hand off work to another guy who will vet it and integrate it himself.

The second point is the heart of my question. I've learned the hard way not to trust the knowledge of my colleagues absolutley no matter how many years experience they claim to have. At least not until they've demonstrated it to me a couple of times. So given that whenever I develop a piece of firmware, if it interfaces with some technology that I don't know then I'll try to learn it and develop a piece of test code that helps me understand what they're doing. That way if my piece of the product comes into conflict with another piece then I have some knowledge about possible causes.

For example, the PC guy has started implementing his GUI's in .NET WPF (C#) and using LibUSBdotNET for USB access. So I've been learning C# and the .NET USB library that he uses and I build a little console app to help me understand how that USB library works.

Now all this takes extra time and energy but I feel it's justified as it gives me a foothold to confront integration problems. Also I like learning this new stuff so I don't mind. On the other hand I can see how this can turn into a time synch for work that won't make it into the final product and may never turn into a problem.

So how much experience/skills overlap do you expect in your teammates relative to your own skills? Does this issue go away as the teams get bigger and more diverse?