You make a very good point with respect to the value of the SPS you burned. A black foil rare would certainly benefit you more in terms of game play today ( and currently conflict points), and potentially a future land worker.

Given your high SPS earnings I'm going to guess you have plenty of glint to get the reward cards you want, trick out your exemplar, and splash out on the odd Splintervibe.

Where burring SPS for glint makes more sense is when you are further down the totem pole, speeding up your reward card levelling may be appealing.

Having said that, I am certain I'll max out the rewards in time, so that's just a patience game, and personally I do not have enough SPS, so burring it is not appealing to me as a smaller player either.

On a related note ; Now that scholars are visible, I was shocked to see one Scholar with so many games played over so many accounts in the Diamond leaderboard, a couple of days ago I added up the matches played and with an estimate of 3min/match, that one scholar had put in 100 hours of game time, in what was it ? 7 or 8 days ?, maybe they are faster, I don't know. It did give me pause for thought, and not in a good way.