I have taken many courses and continue to do so.....it's all about upping your skills and not just relying on the basics you were taught at foundation level.
To be a successful and sought after nail technician, you need to be updating your skills at least once a year and doing your own CPD, whether by networking here, going to the shows, attending workshops, reading trade press, that kind of thing.
Foundation level is foundation level and to be honest, it's very rare that I have come across nails from a tech with only foundation level qualifications who can really cut the mustard....obvioulsy there are exceptions to the rule, but in general IME I would say not.