SIF Folio H1 review: ahead of the market, but have I over committed?

The old stock market adage suggests we should “Sell in May and go away, don’t come back until St Leger’s Day. The St Leger’s Stakes is a horse racing meeting that takes place at Doncaster in mid-September.
The idea harks back to a time when stock trading mostly took place in person on exchange floors, and market participants liked to take an extended summer break.
This notion should be archaic in today’s always-on world of electronic trading and global financial networks. But we have indeed seen a mild market slowdown since mid-May:

This prompted me to look back and see whether I could recognise any seasonal pattern in the performance of my rules-based SIF Folio.
I reckon SIF has fallen between mid-May and mid-September in four of the eight years since the model portfolio’s launch in April 2016.
This even split suggests to me that I can probably dismiss the idea of selling up for the summer as a trading strategy. As usual, I plan to continue following my trading rules. But there’s no doubt that SIF’s ninth summer has begun with a marked sell off.
Since hitting a record...