You'll come to learn that you need to save up these buildings and then just place them at key times, because they only last 5 days, i.e. place them when you're about to start the first round of a tournament and it will be active for that whole tournament. Alternatively place them when you're about to start a Spire week and it will be good for that whole Spire. For more advance techniques you can think about when you play Spire and tournament rounds and get them to all be done within the boost of one ELR.
Also, there are good and bad times to use a building that only boosts Light Ranged troops. You've picked the perfect time, being in the Steel tournament because your predominant enemies in the tournament are Mages, which are vulnerable to LR. You may have done that on purpose, so ignore me if you're already aware.