This is prompted by this question but I am fairly sure I do not have the correct answer so I am making this one.
My personal answer to "How do I get my data from company X under GDPR" is to find an email address and send a Subject Access Request (SAR). To find an email address my first step is first to look for a gdpr contact, or any other general contact email, on the contact and privacy settings pages. If that fails I search their website using something like the commands below . Try the company mantioned in the other question this method failed, and this is the first time this has happened. I tried googling, and with the help of a website designed for this purpose I found a list of emails. There are none that are obviously suitable for this purpose (dpo@, gdpr@, contact@, sales@) but there are emails that match the executive team on their homepage.
My understanding is that a SAR sent to any member of the company is valid according to the letter of the GDPR. I am quite sure the company does not want to get GDPR SAR's via their executive team. In any followup the requestor may be looked upon less favourably because of this obvious inappropriate route to make a SAR. On the other hand, perhaps the company will be looked upon less favourably because they made it so hard to find an appropriate email contact.
Would it be within the letter and spirit of the GDPR to make a SAR to the executive team of a large company if those were the only email addresses on the web?
Note they do have a contact form, but email is much better for making SAR's. Partially because it takes much less time, especially if one has a template, but most importantly because it gives one evidence of the time a SAR was made in the event one reports the interaction to the authorities.
$ wget -r https://foursquare.com/
$ find . | xargs grep "mailto" | grep "foursquare.com" | grep -v "jetpack" | more