[Heliosmaster]

Energetic collisions can send debris on higher orbits with significant longer time to decays. It all depends on kinetic energy added

[Rebelgecko]

If pieces got bumped into a higher apogee wouldn't their orbit end up with a lower perigee as well? If so I think that might actually be better for deorbiting quickly

[meowster]

As long as it doesn't hit something while it's in apogee.

[throw9474]

Diffuse debris while at higher orbit can take out satellites in those higher orbits (like Iridium, Kuiper, etc..)