It’s left to our judgement, Opticians Act doesn’t prescribe methods, only outcomes.
That said; your method has to stand up to scrutiny and has to allow you to be as competent as the average practitioner. Additionally, if you’re a College member then you are obliged to comply with best practice methodology. That’s definitely not routine use of Direct Ophthalmoscope, it’s a second choice instrument nowadays, you’d need to be able to justify why you chose to use it and having floaters wouldn’t be a good reason!
In practice; Volk is largely superior to indirect, dilation is required much less often and doesn’t need to be as bright. I’ve used both and I much prefer Volk, with Direct being a rarely used second option.