I've had the problem with the advanced strength increases you mentioned, but you have to be wise about it and let a couple workouts go by before advancing your numbers, because....you might just be having a good day.
As I'd mentioned in a thread I did about charting yourself with colored markers, I come close to failure here and there (indicated by a yellow dot: caution) and otherwise highlight my finished numbers with green. If I cannot do a final rep or more, I cluster them to get the workload done, mark a RED dot on that square and repeat the same weight next week, or until I can do it without clustering, rest-pausing, or poor form. Actually, NEVER USE poor form! Then I advance the number. I end up with a page full of green squares with some scattered yellow dots and an occasional red one. But my numbers just keep coming up and up.
So, in trying to keep my chart and workouts where I want them, I have had to add more to the charted weight if something was too easy
halfway through the minicycle (15, 15, 5's...or 15, 12, 8, 6's as I did once)
Don't forget ta EAT!