For some firms this will be the case. For instance, I think (if I remember correctly)
Linklaters state you need a certain number of weeks of legal work experience to go forward for their direct TC.
But for most firms it won’t be as simple/binary as needed a certain length of work experience. Some firms will look more at your work experience holistically (both legal and non legal) while others may look at your motivations and other evidence for pursuing a commercial legal career and weigh this up alongside your work experience. For instance, if you can show strong and clear motivations and show other evidence of learning more about the career outside of legal work experience, this could replicate (or be stronger evidence) than describing a vacation scheme experience.