To be or not to be?
IO540
If there wasn't a need for services such as FIS then they wouldn't exist. They do exist because they are required and that is why they are valuable.
Navigation skills should be obvious I agree. However many factors lead to infringements. The occasional pilot is particularly vulnerable to overload, however so are many more experienced and professional pilots. It would not be correct to say that professionals do not screw up but only PPL fools do. You shouldn't take my remarks to mean only the PPLs who are members of my club are the ones that have got it wrong.
For the single crew pilot who is; pilot, 1st officer, navigator, radio operator and flight engineer the assistance from a FIS is worth every penny. As I said previously the RADAR facility is only one part of the job.
Infringments happen not because of bad planning necessarily but often as not owing to unforseen circumstances (perhaps bad planning) and /or overload. At these times the FIS will be a second unreplacable member of the crew.