Googling the subject, it seems there is a historical limit of 13 chars. By experimenting on my E30 (editing a track name on the device) it will take names 31 characters long (this is the Track name not the file name) but only the first 19 are visible in the menus, so any information placed after char 19 is useless. Other models have other limits.
Some software (I'm tempted to say, good software) will adhere to the older 13 chars limit or some other low limit. But possibly truncating without warning. Then if you have put your differentiators (1, 2 etc) at the end of the name they can get lost and conflicts may arise due to duplicate Track names. Such conflicts might get resolved by automatically renaming with 1,2 etc at the end - but not necessarily in the same way that you had numbered them originally!
When differentiating between similar track/route/waypoint names it makes sense to put the differentiator first, even though it can feel a bit ungrammatical.
So 1ROUTE 2ROUTE 3ROUTE etc, or if going over 9 it would need to be 01ROUTE, 02ROUTE, 03ROUTE - rather than
ROUTE1 ROUTE2 ROUTE3 which is just a waste of the 1st few chars really.
And Waypoint names should be kept short (I use a personal limit of 6 chars, and would certainly advise no more than 9) to avoid screen clutter in various situations.