I only have 3 strikers at my club, it's enough because I only play with one striker most of the time. The others are 2nd choice strikers or emergency replacements. Sometimes I think Suarez lacks intelligence. He is 1 on 1 with the keeper and decides to pass to a defender who usually misses lol. Happens a lot of the time, he's great when he doesn't do that.
My new signings will be a year older next season at 6*, they will get to 7* through a bit of PT and regular matches. The cycle will continue for a few seasons at least because they'll be fast trainers until they are at least 24 years old. Jonny Lamb is 23 now and one of my fastest trainers... He was a youth player from level 1 and I still have him to this day. If I stick to this regime then I won't have to buy scouts and just invest in buy young players and give them a special ability.
At 5*, my young players gained at least 50-60 SP a day and quickly got their special abilities. It was about a 1:1 ratio for rest packs to SP, maybe a bit better than that so it's definitely more value for tokens than scouts. You also get to pick the SA which I like.