well, the good news is that it isnt necessary to glide toss every single time you have a banana in your hand. You can do it, cause its not hard, but sometimes its just better to just chuck it.
I personally have 3 reasons why I glide toss:
1. glide toss a banana down and slide backwards as a defensive measure. I use this either when someone is rushing me on the ground, or coming down with a dair of some sort. This gets them to slip while you are in a pretty good position to get a free attack off. I tend to go safe and do a dsmash more often, because sometimes i try a stutter step'd fsmash and mess up and end up doing a dash attack, which isnt all bad but clearly isnt what i was going for.
2. Glide toss a banana forwards and slide backwards as a defensive measure, or to get near a 2nd banana. doing number 1 for defense against someone with a ranged dash attack like an ike isn't gonna help any when theres a sword in your face. Or if you are both standing still, a great way to both get away from your opponent, and get them down at the same time. Another use is to do it so you are near your 2nd banana (if you have one out) so you can easily hit A to pick it up instead of worrying about dash attacking to get it and going out of your way
3. Glide toss a banana forward and slide forwards for offense. This one will get you close to your opponent as they slip. Best method if your style is to work with 1 banana instead of two. Keep it up and you will eventually have them at the edge of the stage and in range of your fsmash/dsmash. Or you could stop the glide tossing at anytime and be close enough to just run up and grab and fthrow them.
Another general rule of thumb is that when you throw a banana regularly it can sometimes be spur of the moment so you dont become predictable, but due to the effects of the glide toss, you should always have a reason/method to your madness as of why you are glide tossing. Glide tossing the wrong way or for no reason will do nothing but slide yourself out of position to follow up quickly
hope that helped, sorry it was so long