Theory: Everything Memory & Memory Management

Let's get the obvious out of the way first, the less memory you give to your opponent the better. The question we should ask is how worth it is it to keep your opponent's memory at a minimum because sometimes it would require a sub-optimal turn to keep the resulting memory at a specific value.

The Magic Number 3

3mem tamers set you to 3, lv6s with effect cost 3, lv3s with effects cost 3, etc etc. Many elements of the game is balanced on you having 3 memory, hence why lv6s with 4cost and no impactful on evo effects are awful, because there is no way to guarantee 4 memory.

There's little difference most of the time between 1,2 memory because the lv5s with effects and lv6s all cost at least 3, thus it would be your turn regardless. Meaning it is sometimes worth it to give your opponent some extra memory if it would enable a play for yourself next turn.

The usual evo costs are lv4=1/2, lv5=2/3, lv6=3. Thus you can predict/control what your opponent would play given 3memory. This is also why decks with the ability to ignore this general rule (green, with download and Hidden Potential) is so threatening, because all they need is a lv3 body and 1 memory to evo all the way to a lv6.

Adjusting your Memory Strategy In different matchups & scenarios

Say your are affraid of a hard summon Bushiagumon into lethal, rather than just keeping your opponent at 1 memory, you can keep them at 4. Scared of Blinding light as well? keep them at 2. 

Against a Mega Zoo? Practically little difference in giving them 2memory and 5memory, unless they can evo on an existing body, they are just going to hard summon 1 big digimon and pass the turn.

Understanding the max memory you can give your opponent while keeping them out from specific plays, greatly increase the number of options you give yourself.

Giving Massive amounts of memory to the opponent

RNG is an inevitable element of every card game, you will encounter unlucky games with a full hand of lv5/6/7s. Many would be scared to hard summon a big digimon giving a lot of memory to the opponent and opt to end turn give 3 memory instead.

Assume your hand was nothing but lv5/6/7 hard summoned a 7cost lv5 turn 1. What can your opponent do with 7memory? a removal option like ST-Terra Force isnt the end of the day, he passes 1 memory back to you. A cheaper removal like BT2-Eden's Javalin? at most followed up with a lv3 or evo up to lv5 in breeding. The worst case scenario would be a chain evolved up to BT1-Slashangemon or a BT2-Chimeramon deleting your lv5. However if your lv5 lives, you instantly enable the rest of your hand and can start evo drawing.

Take Mega Zoo decks for example, their whole game plan revolves around hard summoning big digimon and betting their opponent has no way of removing it. There are currently a very limited amount of good removal in the game, it is not as devastating as you think to hard summon a big digimon.

Memory Controllers

These cards disrupt the normal flow of the game, allowing for surprise turns. The mere existence of these cards would make your opponent rethink their plan and try to play around them whenever possible.

The massive impact of the above cards has made these lv3s a great inclusion. Not only does it stop Chaosmon VA's On Delete effect it also stops a security Hammer Spark.