I have dell XPS, it had perfectly functional sleep and could be put in a bag. Then 'modern standby' was added in an update and it ruine the laptop - if I place it in the bag in the morning, by linchtime it will be crazy hot and the battery will be gone. And you cannot diaable this feature. I don't get wtf these people are smoking.
On my Dell, this problem happens when you suspend the laptop from software (either with pm-suspend or systemctl suspend). If you simply close the lid, it seems to enter in a different "mode" of suspend, the real one, where you can carry it without overheating and the battery lasts for weeks.
