Hi,
are you only talking about points or also what learning style makes more sense?
IMHO you should NOT be using the “speed reviews” to actually REVIEW words/phrases/sentences which are in your backlog (to be watered).
Speed review is only about multiple-choice, so it is testing your remembering, not the RECALL phase of your knowledge, just like DuoLingo mobile apps.
For watering words on Memrise on the web interface I STRONGLY want to suggest you to use Cooljingle’s “all typing” user script combined with several others: “catch up review”, “wrong answer skips”…all scripts run together with the Memrise timer disabled by “Memrise timer disabler” user script.
When you have to type the words in the target L2 language, you are actually being tested on RECALL.
The points vary for each word (I get from +45 to +134 / +150 points max; probably depends if I water it the same day or how many times I got the words right in sequence??).
“All-typing” (including settings on the left side) is really really great if you have to type in the phrases or even longer sentences.
You can only manage this if you disable the timer.
I would ONLY use speed reviews on finished courses when there are no “words” to be watered in the backlog.
Yes, it may be fun from time to time to quickly select one of those words options you are shown on the screen.
IMHO this may further train your knowledge on old words (for good), you have not to be tested this day or week (soon), because their SR interval was put more back already by the Memrise algorithm.
Please note that you will NOT get up to 134/150 points per word if you use the speed review for active watering!!!
600 to 700 words in hour: Man, that is more than crazy 
I am almost sure that you will not retain almost anything the next days as I really hate the speed review timer (especially on longer phrases/sentences) if you do so, don’t you?
My suggestion would be to not let the backlog queue fill as much as 600-700 words 
Or even better: If you really have to do so, to break the review into multiple 100 words x Y session steps to get the backlog queue down effectively.
With Cooljingle’s user script “infinitive learning” you can e.g have multiple 100 words review in a single review session, without having to restart the watering each time manually.
100-200 words review (all typing) is IMHO more than enough, or let it be maybe 300, that aftger that you should take a small 5-10 minutes break afterwards before you start the next review session.
The user script “Memrise Catch up review” really helps to keep your review backlog queue down, even if you maybe miss watering for a 3-7 days or even 14-21 days break of actively reviewing “words” (e.g on finished courses).
You shall recall/remember words/phrases/sentences more and more even next days / weeks after a review (you should see a constant improvement).
Therefore it does not really help IMHO to run through (quite long / exhausting) watering sessions, just like it does not help too much to quickly run through a DuoLingo tree (skills) or even use the mobile apps for strengthen excercises, which the SR algorithm would pick.