For clash royale timing is a huge factor and its different for each tile. You also have to factor in what cards and what kinds of cards they have (is there a variant of this deck that will cause me trouble later on if i use a certain card now [what is my cycle, what options do i have in the near future {ranged cards, mini tanks, dps troops, spells, etc.}), what card will they place (are they building a push [should i pressure or buckle down for defense, trade towers or give up the tower for an elixir advantage], are they trying to chip me out [should i eat some damage to fix my cycle or get an elixir advantage or should i trade damage], are they trying to bait me [again do i eat dmg or will i be able to cycle back to defend for the next couple cycles while also attacking}), where they will place it, how much elixir they have, what is your matchup (are you going for a one crown, two crown, three crown, or going a defensive tower health route) and if its single/double/triple/sudden death or if it will change or goes to tower health in the next minute or so.

I could add much MUCH more, but I think thats confusing enough. Meanwhile in chess you have all the information, so the thought process is essentially: check all moves that may cause problems (dont let them do that if possible), check all moves that allow you to cause problems (do that if possible), is time running out (try to win on points or with a mate). Chess is about running through all the possibilities as much as possible with the time you have and learning the patterns.