Maximum value for "CatchupParallelBlocks" in config.json for mainnet


my algorand version is:
$goal version -v
Version: [v1 v2]
GenesisID: mainnet-v1.0
Build: 3.5.1.stable [rel/stable] (commit #aa2fb0ee)

On the website default value is written as 16. What is the maximum value that can be set for the parameter -CatchupParallelBlocks- in config.json file?

Secondly, if we edit the config.json file, should I restart the algorand node for it to use the latest config.json file?

Hope to hear from you soon.