Is the length filter required when checking if a field has content or not?
You can probably get away with removing |length for most conditionals that check for the existence of content in a custom field and just check on entry.fieldHandle instead.

One exception to this would be for lightswitch fields, which always return true for a |length check, but return true or false when checking on entry.fieldHandle depending on whether the lightswitch is on or off.

StraightUpCraft has a great article on Testing if something exists and another on How to check if a variable or value exists using Twig, which cover a multitude of cases and ways of accessing variables using Twig.