I myself am pretty specific about what I do against certain characters. Player tendencies are definitely a factor, but character does matter. Here's a small list of things that I believe sincerely help to go by in most cases.
- NEVER throw a random 5D against Tao, Arakune, or Bang. Chances are they'll be in the air before it reaches them. However if you're pressuring them in the corner then it's probably ok.
- Deeply consider 2D when against Tsubaki and she's in the air. A lot of the time she'll probably try to dive in at you and will usually get hit by the 2D, which can spell a lot of hurt if she's close enough to land a 214A afterwards. If not, then a Rapid Cancel'd 2148D can work pretty well too.
- Do everything you can to make sure you don't whiff a 6D against Ragna, Valkenhayn, Tao, Bang, Noel, or Arakune. Those characters specifically are way more than capable of punishing it badly.
- 2D is fantastic for sniping Arakune out of the air.
- A lot of Tagers like to jump and green shield while they move towards you. A great thing to keep him away is to chain 2DD > 6DD > 236D. This will push him back and force him into a bad position when he's back on the ground. If he's using Sledgehammer, just back airdash or try to land a 236C (requires decent timing). Other than that though you can zone him all day as long as you're not in range of a sledge.
- Zoning is absolute key vs Litchi. Her normals are too good for Lambda to handle. This matchup is really a big game of keepaway, and probably the best matchup to learn great zoning skills.
- Avoid using too many 5C spacing techniques against Tao or Makoto. They'll just go right under it and punish you.
- Hazama is a real pain. He can outzone you any time of the day with his chains. Key here is predicting whether the player is going to jump or not and how high if he does, and make sure you toss a sword before he throws his chain. His chain is faster, and can hit opponents at more angles than Lambda. It's also a pretty good idea to try to learn the spacing of 236C specifically for this matchup. Catching him with it when he jumps for a chain is always great and usually pretty safe.
That's not everything but it's good advice in general imo.