Does it make a difference how many .trn files there are, if they cover the same transactions?
You need to understand that while restoring a T-log, you cannot restore a T-log backup which is out of sequence.
for e.g If you took log backup every 5 mins for 1 hr then to bring the database up-to-date, you need to restore all the 12 T-log backups in sequence after fist restoring the full backup.
Keep in mind that all except last, restore should be done with norecovery. Last one would go with recovery.
As @maxVernon mentioned, taking frequent backups will help you bring the database more up-to-date and you have the flexibility of getting Point-in-time recovery in case of any disaster.
For fast or slow, obviously, a huge T-log will be slower to restore than a smaller one as it has to redo / undo all the operations that have happened since the last full backup to bring the database in a Consistent state.
Some excellent references can be found here and here.