Hello Anthony,

You raise a couple of questions and I'll try to catch them all:

You wrote:
However I would have thought that if you have 10 tasks each one taking 2 days and one developer working on it, you should be able to list them without any preceding task and because they are all being worked on by the same resource, then all of the tasks would expand out from taking 2 days to 20 days?

Yes, you can but it doesn't happen automatically. If you have assigned the developer to all 2-day tasks at 100% (or max units) -- the resource is overallocated because all of the work is scheduled at the same time. You can use the Resource Leveling command (Tools menu) to have Project delay tasks until the overallocation is resolved. The Resource Leveling command will delay tasks so they are spread out and the resource is doing one task at a time.

Another option is to assign the resource to all 10 tasks at 100%. Then change the task type to fixed work and then change duration to 20 days. Project will spread the 16 hours of work over the 20 days for each task and calculate 10% assignment units. This method assumes that the resource is working on all tasks at the same time which in reality they are not.

Given an option, I would either link the tasks (as you suggest) or use the Resource Leveling command. I think both are easier to understand the resulting schedule.

You wrote:
If you were to get another resource, so in theory halving the dev time, if you have task type set to fixed work, you'd see the time line go down by half.

The reason the time (duration) drops when you add another resource to the task is because the task is effort driven. Fixed Work tasks are, by definition, effort driven but you may also work with fixed units and fixed duration tasks. Fixed units and fixed duration tasks can be non-effort driven.

You wrote:
My problem is that they are not working on the same task together, dev Bob will work on tasks A-E whilst dev Dick will work on tasks G-J. So is this a case where a PM would go into MS Project and delete the dependency of task G on task E and set task G to start at the same time as task A but with dev Dick working on the second set of tasks?
Given the scenario you list, I would remove any links between G and E and re-assign. You can also re-assign Dick to Bob's tasks and re-level if you have used resource leveling to resolve the issue with Bob in the first place.

I hope this helps.
Julie