In the programming world, there is this concept of "Bootcamps". They come in different flavors : from free retreat centers like Recurce Center (similar to Writers' Retreat) to paid bootcamps. They are usually of a few months (2-4 months), and rapidly add to the peoples' skillsets.
Are there any such bootcamps in Maths? Perhaps, they are called by some other name than "bootcamp". My focus is on adults, who have had a basic education in engineering mathematics or a minor in mathematics and now wish to return to strengthen their skills further, however are impeded because of a lack of a Maths Major.