Well, for my "end of 2017 year Spanish challenge" I found it pretty boring to get penetrated with exact the same sentence once I answered the question wrong.
Where are those varying 3-5 or even more sentences per single word?
Lingvist IMHO heavily focuses on error repetitions (<4h interval) within a 30-60 minutes "learning session" and repeating over and over again the old sentences by dynamically adding those words back to the "repeat practice steak".
Memrise at least "supported" with a user script to tune 3-7+ repetitions down to ONE error repeat in a single review session.
The default of Memrise was three before, and making errors could easily bring up the same word in the same session 6-7 times.
That's way too much!
If I do this ONE error repeat wrong, I may get 2-3 repeats in total.
I can live with that.
I can somehow also skip over if I really do not want it once the progress bar is almost at it's end and just those few "incorrect word repeats" showup.
And if I did not know the word, it would not come up for the next review sooner than 4h (red, very wrong) / 12h (next interval after 4h or yellow almost correct answered), so I can focus on other words to review from my backlog or learn focus on NEW words in a defined 10-15++ words session.
Memrise of course has for the 1-7 courses the same (fixed) sentences, but with a bit more air (4h / 12h / 1d) it is not that annoying to repeat them.
I am not sure what exactly I "learned" with my 1000 Spanish words challenge.
"A bit of Spanish"? Yes, it was very nice for me to compare my 1,5 years knowledge of Portuguese to Spanish on Lingvist with it's superb high quality Spanish audio!
Have I learned all the sentences?
Have I really learned the words and verb conjugations and tenses?
I may find out when I will be back to Lingvist Spanish reviews one day when I have progressed with my two Portuguese reverse trees... ;)
On those days where I learned 2-3h / day on Lingvist to push 50-100 NEW words limits, I was hardly able to detail review the tips may it either be grammar, person conjugations, tenses, etc.
The more time I wasted, the faster those "error word repeats" kicked in!
You really should focus not more than max. 10-20 new words / day on Lingvist!!!
I put much more time than 20 hours into DuoLingo, learning sequentially skill by skill, lesson by lesson, "tips and notes" grammar one by one and Memrise in parallel, to learn and memorize Portuguese.