Passed the 1Z0-810 in December 2016 with a good score.
At first I asked Mikalai Zaikin for his material (I paid for, price was fair). I copied the questions from the quiz to a word-document. 104 questions = 208 pages. All are numbered. It took me about 10 minutes per flash-card for formatting.
Then I transformed the document to PDF and afterwards I printed in groups of four (2x2) odd pages (only the questions) onto one sheet. After that the even pages (the corresponding answers) horizontal reversed were printed on the back of the sheets. After cutting I had 104 flash-cards for the time during may way to/from work in public transport. That was the main part for learning.
Next I took the description from Mikalai Zaikin and made my own flashcards, but only points to remember like API-calls and things to divide up. Here I have written 213 ones.
After having learnt by the flash-cards I did some practice for special questions and get the feeling for it. I did not sit a lot at the computer.
The test by itself: the questions were very mixed, not one theme first, followed by the next. You need to now some APIs calls like Map.compute() or LocalDateTime.isAfter().
You should look for, that static methods can only call other static methods. Be carefully looking for the arguments in the calls, like in Files.walk(.). Next you have to look, that in most situations you cannot add calls after terminal operations of stream, but with exceptions. There were more questions about interfaces and the Date/Time-API than expected.
The maximum time is 150 minutes. I marked questions, I had to review, about 15 of 81.
It took me 106 minutes for answering all the questions.. After a review of the difficult questions and a further quick review of all questions I had quarter an hour left. The difficulty and the length of the questions is very different. The last ones were easier and shorter.
If the multiple-choice asks for more than one answer, the test-programme will inform you.
Time from start to test: 9 - 10 weeks
Thanks to Mikalai Zaikin, which reduced my preparation time enormously.