I have ridiculous feet. They are short, wide, with a high instep and my ankle-bones protrude. I am therefore one of the UK's most prolific purchasers of shoe-stretch spray. I must have tried them all...
I like this Woly spray because (a) it works, (b) it comes in a bigger can than most and (c) it is the least expensive.
The toughest test was on a pair of Loake traditional brogue ankle boots. These hand-made boots are built to last - the leather is 2mm thick. Literally tough as old boots:-)
Initially, although they were wide fitting, the boots were cramping my little toes, my instep and my ankle-bones. A crinkle appeared in the leather above my instep, that I thought would cripple me, if I ever went out of the house in these boots.
I applied the spray over the course of several evenings, whilst wearing the boots. I would spray them at intervals of maybe an hour, whilst progressively tightening the laces.
This patient application has paid off. The boots now fit perfectly. The crinkle over the instep has disappeared and the tops of the boots have moulded to fit my protruding ankle-bones. These tough boots are now so comfortable that they are a dream to wear.
I have also used this spray in conjunction with wooden shoe trees that I have modified to apply pressure on the shoes where I need it most. But I think that the most effective way to use it is to actually wear the shoes, be patient and be prepared to give several applications over several evenings.