How do you apply potion effects to players?

Without time limit you make the time in the command as shown above from 10 to 100000000. Not preciesly so many zeros but much.

I don't know if this is what your looking for, but here it goes:

For speed effect: /effect @p 1

If you want it for longer or faster, do it like this: /effect @p 1 255 10

Hope this helps!

Speed Effect:

/effect @p 1 10 100

You can swap the 10 with any higher number. This specifically is how many seconds the effect lasts.

/effect @p {ID Number} {Number of seconds} 10 Switch the 10 out if you want.

This is my way. I'm using regeneration

First type this command in: /effect @e regeneration 120 [hideparticles]

Then, put the command block on a clock system

I never tried it so if it doesn't work, just say it in the comments and I'll fix it.

You can do

/effect @a minecraft:jump_boost 2 10

This gives Jump boost two to all players for 10 seconds. The command is

/effect (player, @a or @p) minecraft:(potion, with _ between two words) (level of potion such as jump boost 2 or 3) (number of seconds, 255 max, more for unlimited)

/effect give @a minecraft:jump_boost

@a means all players, you can also use @p (nearest player) or @e (all entities)

you can replace jump_boost with any potion effect (like slow_falling poison speed_boost)