I've forced the habit upon myself to first compose a SELECT statement and verify that it will give me exactly the dataset that I want to run my operation on. Then I wrap that statement into a CTE and run the DELETE / UPDATE on the CTE.
This is the one I use too. Tiny difference - I write
select * -- delete
from sales
where customer = 1
so it's even harder to accidentally highlight the 'delete' part.
Although I've switched to DBeaver for a year now, and it automatically pops up a warning when it detects a DELETE query without a WHERE, which is very nice.
DBeaver has something even better, albeit sometimes annoying: you can define a connection as "Production" (highlighted red) and "Test" (green). On Production systems, DBeaver will ask you for confirmation for every write statement.
It doesn't save me time, but a lot of nerves.