If you noticed I included a section explaining when a split test makes sense and you can tell that Booking.com fit it that criteria as they were already starting to grow a lot.
Considering something "optimized" is always going to be a struggle of almost perfectionism (even for myself and my own website haha).
I think you should always be critical of what would be better use of your time: optimizing vs getting more (targeted) traffic ;)
I think if you think small tweaks are all you have left that you need to consider how can you make your website specific to each persona you have on or even dig through which type of people could benefit from your product even outside of what your currently targeting.
Thanks, glad you liked it. This it's something I've noticed people need to come back too when they focus too much on conversions.
To answer your question that totally depends because in the end what you'll need is cash flow to maintain that reinvesting process and that's something (finances/management) I'm not an expert in :P
I understand your point, it's definitely something to consider as I'm still trying to find ways to write the best or most actionable articles possible.
I don't know where it would be documented either as SaaS Landing pages usually require a different explanation as every niche needs a specific strategic!
The main point of that article was showing strategies that you can replicate for each scenario (social proof, intro, product explanation...)and I think you got that ;)
If you noticed I included a section explaining when a split test makes sense and you can tell that Booking.com fit it that criteria as they were already starting to grow a lot.