If your short on time skip to 6:35 for the summary results, the footage prior to this serves as proof of the tests done(it has some math involved) I should probably mention that the consecutive day boost is based on # of days the fertilizer stays on the plot and increases when it is used up; it is not based on amount of times you harvest a crop and no you cannot increase the consecutive day buff if your plot doesn't have a plant even though it has fertilizer. Switching the crop will not change the consecutive day buff unless the fertilizer/boost type is removed or changed. Also I'm not the only one testing fertilizer but others have also pointed out that weird stuff happens whenever you use speed boost; hence why its hard to get consistent results aka no one really can get consistent results to save >1 days for +9 day plants. Edit: On the updated news on discord S6 clarified that speed boost fertilizer saves only 1 day per every 2 days(although from testing on the video I only saved 2 days out of 9 so the odds of speed boost working is quite low)