SPF allows ten DNS lookups. Go over and it fails.Not with an error — receivers just stop trusting the record. This resolves your whole include chain and counts the real total. Need to build one? The record generator does that.
–/10
Resolving
Following every include, redirect and a/mx mechanism.
Your record
The SPF record published at the apex.
Lookup chain
Every mechanism, and whether it costs you a lookup. ip4, ip6 and all are free — everything else isn't.