Just did another upgrade from Lubuntu 24.04.5 LTS version to Lubuntu 26.04.1 on the Wife’s 13 year old laptop and all went without problems and so far everything appears to work.
I’ve had release-upgrades take much of a day (10-12 hours anyway!) as the process varies a lot based on a number of factors including CPU, RAM, number of packages you have installed (my installs are somewhat bloated so lots), speed of internet (mine is slow) etc.
Sure, release-upgrades shouldn’t take that long for most people, but there is great variation in where we live, our hardware, and what we have added/changed on our installs & more.
This area is for discussions around Lubuntu and not support. If you want or need support, I’ll refer you to Support and Help - Ubuntu Discourse