Hmm... given those 3 depth factors, how would you rate Leona (well, windows is pretty obvious but meh).?
From my point of view, there is little to no tactical depth on Q and W, and the part that could be called so in her innate is waiting for your allies to proc your damage (so part of her depth is 100% reliant on allies). Even then, E and R aren't the biggest skillshots. Sure, pros will flash away from the E, dragging Leona under tower, or move away from the ult during that 0.5s cast time, but to the common mortal guy, Leona having skillshots is nearly a joke.
As I said, when talking about windows of opportunity/power, she does offer some great ones. Using E's uptime as a zoning tool, timing your "facetanking" with W's CDs and chasing based on Q's cd does offer for a bit of depth, but I feel like "windows" is the weakest of the 3 depths since it's implicit. Champions will always have times when they are stronger/weaker, especially when you factor in cooldowns.
Lastly, for Strategic Depth, I feel like most of what Leona brings, Braum, Dr. Mundo, Renekton and Jarvan IV all brings. Except for the ignite on Mundo, I would play against those 4 in a fairly similar fashion, and the results of the fights often wouldn't vary by a lot.
Would that mean that you consider Leona boring? Or do you have another point of view on her that I can't see?
If you prefer other champions to discuss on, I feel like Ashe (lacks mainly windows and tactical), Ryze (tactical and slightly windows), Poppy (Strategic/Tactical), and Annie (Tactical, Strategic) are other fair outliers.
N.B. problems further explained :
**Ashe : ** Her one window is "is my ultimate up". Ohtherwise, you can say her passive offers another window, but it's up so rarely and so often is wasted on minions that it barely counts. Also unless you're early in the game, the 100% crit often won't change your play pattern since it will simply add 1 more crit to the fight among many. In term of tactical depth, she has 2 skillshots, one which is sometimes blocked by creeps, sometimes not and otherwise has gigantic range and width so it's pretty much a coin flip in the worst case, and a mana->damage trade in the best one. I really feel that Ashe is one of those champions that feel terrible to play, since your only "WOAH!"moment comes once every few minutes with your ult.
Ryze : His "windows" aspect is pretty terrible. Early game he's "weaker" (still not weak) and as the game goes he bomes a raid boss. His cooldowns are basically always up as long as he stays in the fight and his ult is never really down, it's simply "not quite up yet". In term of tactical dept, he has no skillshots, and his skills are all extremely straightforward. Heck, even his strategic depth is not that great, since he has no real "specific" interactions, he simply deals constant magical dps and heals over time.
Annie : Her 2 windows are her stun and Tibbers. Stun is up fairly constantly but doesn't last long. Otherwise, her power level is pretty much the same all game long; she always has the power of deletion if you're careless. In term of strategic depth, she has 2 instant AoE "skillshots". If the enemy wants to avoid it, he has to dodge it before you even cast it. Her 1 true strategic depth is usage of her stun.
Poppy : Epitome of windows. She is among the best level 1-2, ok level 3-7 and then trash level 8-15 where she finally kicks back up to "final raid boss" level. Even in term of cooldowns, her E is a window of power in and of itself, and her R is the tool that allows her to fight 'evenly' during the weak state. In term of strategic and tactical depth, she's really really awesome... if she was alone in the game, since she removes the depth/choices from her opponents. End game, even a support poppy can simply ult the carry with the lowest damage and kill another target with low mobility, This basically turn teamfights into 3v4 every 2-3 minutes.