If you are in the garden for another year, then the way you maximize your FICO score is to never be late or miss a payment 
The "one card reporting" game is for true optimization. And you likely will see some [few] points benefit for running that game. However, because you are not apping any time soon, it won't be noticeable during the next year, because you aren't going to be missing any payments, so your score will be gradually climbing anyway. Was it the "one card reporting" that increased your score during that year? No, it was never missing any payments.
What is your AAoA on your cards? If it is rapidly aging (was very low because you are new to credit) then you gain points for that waiting / aging.
Did you go through any recent app spree? If so, the effect of all those HP fades gradually, 6 months, a year. You gain points for that dropping off.
If you have some level of utilization because you have multiple cards with $X balance, was the gain in score from going to only one card reporting a balance, so your new total overall open balances are now $X - $Y Paydowns? $X is more than $X - $Y, lower overall utilization, which raises your score.
The point is, you will find it difficult (if you look at all the possible factors) to pinpoint how "one card reporting" is going to really benefit you, and in my opinion, the benefit is not that much compared to all the other real gains in score you can generate from simply not doing anything except making certain you never miss a payment. Ever. And lowering overall utilization.
@JcT21 wrote:my AAoA is 2yr 5 months according to creditkarma, which is rated as poor. i have 1 main card that i use, cap1 wmc with a 10k limit. i currently have 3800 balance on that card which is the only card ive let report & the only card i have a balance on. if i do use other cards for reward purposes i always PIF as soon as the transaction posts. last cards i got was discover it & barclay reward mc in july 2014, and amex delta skymiles in december 2014. i have 7 cards total (2 are store cards) and a total of 32k in available credit via cards. since im nearing 40% utilization on my wmc, does that look bad to the fico scoring system? even though my overall utilization is quite low. curious if doing a balance transfer and spreading that among 2 cards to lower utilization on my wmc would be better. never missed any payments or been late. im thinking having 2 cards report balances may ding me more points than having my wmc report almost 40% usage on its own. which that usage will go down over the next few months. ive watched my score rise fairly quickly over the last year or so and the thought of it dropping or might drop, drives me nuts :-)
no app sprees lately and none intended in the future. however due to 2 auto loans back in may & august 2014, i do have a lot of inquiries 27(TU), which 4 are set to expire in june. equifax and experian have me at 16 each with some set to expire soon.
The 40% on one card may have some negative effect on the score, but if you are PIF, it won't last long. Your scores indicate you are generally doing it right. Time will add more points now, not much else.
Have you researched whether you are due for a CLI on your Quicksilver? If you are using it heavily, trying the SP CLI request may help with utilization on that card.
