The problem is with these questions is these drugs work differently on different people. So what happened with me, or anyone else could be totally different for you.
If you look at other medical-related threads - e.g. No more OWO - on here, Hugger-Mugger, you'll see comments very similar to the one I've quoted from Anth.
My GP prescribed Viagra for me about 12 or 13 years ago, when I told her that I'd got a new gf who had suggested I get some Kamagra but that I wouldn't do that till I'd had my heart & blood pressure checked. The GP checked them both, found them both okay and then told me that because my congenital disability led to poor circulation, I qualified for 4 Viagra a month on NHS prescription.
Things went fine for about 10 years when I found that the Viagra was less effective than it had been when first prescribed. I went back and saw a trainee GP who went back to first principles and checked the formulary.
For me, it looked that Tadalafil would now be more effective. So my repeat prescription is now for Tadalafil and they do the trick but I repeat
for me and at this stage of my life.
Basically what I'm saying, OP, is that while some of us on here may have medical qualifications, none of us on here - afaik, anyway! - is your GP. Whom the NHS pays for being so. So why not take your query to her/him?
I'm as sure as I can be that the first GP I mentioned above didn't twig that my "new gf" worked in a massage parlour in a nearby town. And if she had seen me going in that Parlour, then so what??
I'm sure you could tweak your actual situation slightly just as I did and get the advice you want.
I'd also add that
for me, the Tadalafil also produces a semi when I wake up the next morning so that if I felt like - and could afford! - punts on consecutive days, I'm sure I'd be able to.